2026-10-03 20:00:53

Population grows based on births, deaths, and immigration. The Japanese live long, but their immigration and fertility rates have been dismal for much longer than in other developed coutnries.

Births

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2026-10-01 20:02:01

I’ll be trying a few short articles this week on different topics, rather than a couple of very long ones. Tell me what you think

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2026-09-29 20:03:43

Japan is extraordinary.

Why did it develop samurai?
Why did it close down to the world for 250 years?
Why did it forget how to make guns?
How did it go from feudal to industrial in a matter of decades?
How did it conquer half of East Asia?
Why did it later lose it?

You can explain all of these, and more, just by looking at its geography. We’ve started to do this in the last two articles on Japan’s population and its geopolitical priorities. Now it’s time to connect that to history.

How Geography Determined Japan’s Government

As a reminder, this is Japan:

In the previous article, we saw how the #1 goal of Japan is to unify these islands, especially the three southern ones of Honshu, Kyushu, and Shikoku.

The Smaller Islands

Kyushu is so close to Korea that it’s always been the Japanese island most connected to the mainland, to new ideas and technologies, and to maritime trade, which made it one of the richest and strongest early on. But it has few plains, so with just 12M people today, it’s not very populated compared to Honshu.

Meanwhile, Shikoku is so mountainous that it could never harbor a big population and has “just” 3.5M people today.

The Checkered Plains

All of this means that the majority of the population concentrates in southern Honshu, on the plains, because as we have seen, the north of Honshu and Hokkaido were too cold for rice agriculture and double cropping.

But look at the distribution of these plains. What can you deduce politically?

The key thing to notice is that there are scattered plains, separated by lots of tall mountains. That made transportation very challenging: In 1700, it took 15 days to go from Kyoto to Tokyo! What do you think the consequence of this was?

Feudalism.

When it’s difficult to go from one place to another, armies can’t easily move. When mountains divide them, they can use them as defense.

Information is also more time-consuming and costly to gather, so any central power had a hard time knowing how much rice each plot of land produced: There were floods, landslides, earthquakes, tsunamis, eruptions, typhoons… From the capital, it was hard to know what each paddy could actually produce. So locals could easily lowball it, making it hard to tax fully. The local lords knew exactly how much was produced though, because they could inspect the paddies personally. They pocketed the difference.

Mountains also made trade difficult, because carrying goods over them was too expensive. Normally, trade unites, since traders must cooperate and fight against bandits, so less trade meant a weaker unifying force.

But these valleys nestled between mountains were too close to each other for lords to ignore their neighbors, and they vied for each other’s land and wealth. If you think about it, all these are very similar conditions to those we find in Europe, and unsurprisingly, Japan landed on a similar political system for 1000 years.

However, Japan also had a unifying force, the Seto Inland Sea. It was a bit like Rome’s Mediterranean, allowing people and goods to travel cheaply from one seaside plain to the other.

The Seto Inland Sea was not a perfect highway. All the crannies on the coast and the strong currents in the sea enabled pirates and maritime lords to flourish. The same thing happened in the Mediterranean early on, until Rome could fight pirates away. But in Japan, since no plain was strong enough to create a powerful navy to monitor it, the sea became both a unifying factor for trade and a feudal one for political power.

The Long March to Unification

The First Unification: 300 BC to ~700 AD

For about 1000 years, technology moved from Korea to Japan: rice agriculture, iron metalworking, horseback riding… The Japanese simply expanded across the islands, grew their population, and clans emerged in every valley.

As that phase progressed, new technologies from the mainland, mainly writing, Buddhism, and the Chinese-style administration, allowed the state to strengthen. A central ruler emerged in the powerful central Yamato around 600–700 AD.

Japan meddled in Korean politics in the 600s, and when its allies lost to the Chinese, Japan feared an invasion, so they centralized vigorously to organize their defenses. The Japanese settled their original capital in Nara,1 near Osaka and Kyoto, and built a centralized system around an emperor, with a census, written laws, officials, provinces, taxation and conscription.

The Feudalization of Japan: 700 – 1600 AD

This centralization was too expensive for the time, and crumbled. Why?

Under the centralized government, every household was registered in a census, and taxes were due per household. So for example, person A owned rice paddy B, so he had to pay x% of B’s annual rice production.

We saw before how it was difficult for central leadership to know the production of a specific paddy. But also, how did you keep track of the households that had to pay you? People are born, die, marry, move… It was nearly impossible to keep up with it all. The census had to happen frequently, and all that information had to travel back to the capital, which took a very long time and was very expensive.

All of this worked while the system was still new, and while the Japanese feared a Chinese invasion. But as the fears receded, and people learned the system, it became very hard to maintain.

So little by little, power reverted to local authorities, who knew who owned each paddy, what the harvest was going to be, and were able to tax them accordingly. As more money stayed local, the emperor had less money to fund an army, but also less of a need for one, since now the local authorities were in charge of collecting the taxes and sending them to the capital. As a result, the local authorities also had to hire their own local forces to defend against bandits and neighboring clans. These would become the samurai.

Notice how similar this is to the process in Europe! The Roman Empire fell, with its centralized power, census, and administration, and in its wake appeared local lords who taxed local peasants and defended them through the figure of the knight. In fact, just like knights, samurais were also mounted! A key factor of the samurai’s strength was in fact the expensive ownership and maintenance of horses.

Peace and war alternated for centuries, culminating in the Warring States Period (or Sengoku Period), between ~1450 and ~1600. In the late 1500s, a series of leaders2 were able to finally unify Japan. This started the longest period of peace in Japan, the Tokugawa Shogunate, which lasted ~250 years between ~1600 and 1868, and was named after the dynasty of the last one of these leaders, Tokugawa Ieyasu.

Why did that happen then, and not, say, in 1000 AD or 1800 AD? After centuries of military action, civil administration, and new ideas from Korea and China, state capacity had dramatically improved. The only states that could survive were the rich ones that could tax their citizens efficiently and field an army effectively—so, the bigger, better-managed states.

Also, the Portuguese arrived in the 1500s and started selling firearms. This initially created a crisis, but eventually helped whoever was rich enough to buy more, had the right influence to source them, and could learn to use them better. A local lord no longer had any chance against a well-funded one. Firearms also made populous valleys more powerful: A samurai needed lots of training to fight well with his bow, his katana, and his horse, but you could give a firearm to a farmer and quickly make him lethal. So more populous lands became stronger.

Another factor of unification was the discovery of silver mines in the mid-1500s. Those who controlled them could trade with the Chinese and the Portuguese, sourcing more weapons and fielding bigger armies.

Of course, silver means more currency, so it’s easier to trade. This meant more wealth, which could be taxed to invest in war.

Unity at All Costs

Imagine you’re one of these Japanese leaders, ruling after centuries of feudalism and living your entire life in war. What would you do? Spend all your efforts to ensure that didn’t happen again, eliminating all the decentralizing forces of Japan, to be replaced by centralizing ones.

Here’s what the Japanese leaders did:

1. Weaken the military power of potential opponents:

   1. They eliminated the military power of lots of competitors: Buddhist temples, warrior leagues, autonomous towns, guilds…

   2. They forced lords to destroy their castles (except for their residence) and ask for permission to do repairs, and banned them from building more.

   3. Local lords also lost the ownership of their lands. They were now entrusted with the land by the shogun, always on a temporary basis. They were then moved around, so as not to settle too much on a particular land and grow their control on it. This made samurai landless warriors.

   4. The most loyal ones were granted the best lands.3

   5. Marriages between lords required approval.

   6. They ordered farmers to surrender swords, daggers, bows, spears, firearms, and other weapons.

   7. Without wars to fight, the samurais’ horseback fighting became a hobby, and skills were lost.

   8. Only a few gunmakers were licensed, and all were centralized in a single location. They could not travel to other provinces, share fabrication procedures, or sell firearms without reporting first to authorities. So lords could not buy guns domestically or from outside the country. To prevent illicit trade, gunmarkers were given a stipend, whether they sold arms or not. The reduction in volume of sales made firearms so expensive that they disappeared from Japan over the centuries as a weapon of war.4

   9. They eliminated pirate lords in the Seto Inland Sea. Authorities had to identify ship captains, fishermen and other maritime populations, make them swear not to engage in piracy, and threatened confiscation of a lord’s lands if piracy continued within his territory.

   10. To foster trade and reduce enemy income, they abolished many toll barriers and monopoly privileges.

2. Improve income

   1. They ordered a new nationwide cadastral survey: measure fields, classify quality, estimate yield, and identify cultivators, so they knew exactly who should get taxed, and how much.

   2. They linked taxes not to the people, but to the paddies in the village. Each parcel owed a precise amount of taxes in the form of rice every year.

   3. Farmers were tied to the land, so the difficulty of knowing who owed what disappeared.

   4. Control mines: silver and gold mines fell under the shogun’s direct control.

These are the actions to achieve Japan’s first geopolitical goal—unite internally—but remember Japan’s two next geopolitical goals:

1. Protect the five gates towards Japan (four island paths plus Korea)

2. Neutralize Asia’s superpowers

And here, Objective 1 was threatened by 2 and 3, because Europeans started appearing in Japan, while China and Korea had always been threats. So the Japanese leaders addressed these threats, too.

Foreign Affairs

Hideyoshi had a battle-hardened army with no more wars to fight; dangerous to have in your own backyard. And since Korea was nearby and a constant threat, he figured he might as well launch an attack.

This reminds me so much of what Portugal and Spain did after their Reconquista unified the Iberian Peninsula against the Muslims: They kept going. They invaded neighboring northwestern Africa (now Morocco) and started sailing around the world. Fortunately for Spain and Portugal, they had no strong empire nearby to throttle them. Unfortunately for Japan, they did. The land campaigns worked well in Korea, but their naval campaign suffered from a catastrophic battle where it lost a huge chunk of its fleet. The war bogged down, and Japan pulled out when Hideyoshi died in 1598.

The only option left to the Japanese was to hunker down, and that’s what they did.

1. The Japanese people were banned from traveling abroad, under pain of death.

2. Foreigners couldn’t come into Japan either, under the same threat of capital punishment.

3. Trade with foreigners was extremely limited. The Dutch and Chinese were limited to trading in Nagasaki, on the southwestern island of Kyushu, and the Koreans in Tsushima. This notably kneecapped Kyushu lords, who used to conduct most of the trade, but had to stop.

4. The Portuguese, the first to arrive in the 1500s, didn’t just bring weapons. They also brought Christianity, which spread like wildfire in Japan. During the Warring States Period, local lords would adopt Christianity to get arms and money. The Spanish landed in Japan soon after, and the Japanese learned from them what happened to the Aztecs and Incas. The Japanese leaders decided to ban Christianity, the Portuguese, and the Spanish from landing in Japan, and they prioritized Christian lords in the national cadastral survey, to suppress them.

You can see how intense all the policies were to secure Japan’s main geopolitical priorities. The Tokugawa achieved it for good, and the peace lasted 250 years.

Japan’s stability came at the cost of completely isolating itself from the world. But the world didn’t want to isolate itself from Japan.

The West Hurls Japan into the Future

In the mid-1850s, Westerners had just humiliated China in war and forced it to open up to Western trade, as I explained here.5 The Japanese knew the West was coming for them, and it did, in 1853, when Commodore Perry knocked on the door of Japan’s past.

Perry entered Tokyo Bay6 with steamboats that could easily outmaneuver any Japanese sailing ship, and with guns whose violence the Japanese had only heard tales of.

Outpowered, the Tokugawa Shogunate was forced to open up to trade with the West, and this exposed its military weakness after 250 years of isolated peace. This became the downfall of the shogunate: The Japanese split into two camps, one that wanted to expel the Westerners, the other that wanted to co-opt their technologies. How exactly did the shogunate fall?

• After 250 years of mostly peace, the military force of the shoguns was diminished.

• The shoguns controlled a lot of the military power, but the local management was not centralized, still belonging to local lords who knew the local conditions. So well-organized local lords, with the right strategy, could beat the Tokugawa (the feudal nature of Japan still showing up).

• The right strategy was to co-opt the emperor. The same figurehead dynasty had been the emperors of Japan for centuries. It was a useful convention to legitimize the shogunate, with no real power. Seizing the emperor would weaken the shogun’s legitimacy.

It won’t surprise you to learn that Kyushu leaders (and some from the westernmost part of Honshu) were among those who wanted to Westernize: They were more open to foreigners and had already been schooled by their weapons (as Westerners arrived from the southwest and could only trade in Kyushu), so they had started sourcing them and arming up. Eventually, they marched on Kyoto, took control of the emperor Meiji, defeated the Tokugawa in a battle, and “restored” the power to the emperor. The Tokugawa side disappeared. The period that followed is called the Meiji Restoration, and it’s probably the most radical modernization a country has ever seen. The Japanese studied everything about Western powers, adopted it all, and within a decade, virtually the entire economy, military, and administration were Westernized.

This worked so well that by the end of the century, Japan could face the historical regional behemoth (China) and a Western empire (Russia)... and win.

You have to understand how absolutely crazy this was at the time. It changes the arc of history in the east: Until then, for literally thousands of years, everything in that region had become more Chinese. Suddenly, little Japan, an appendix at the end of the continent, where technologies arrived after a lag and never originated from, goes from aligned with the Chinese–Confucianist world to Westernized in a few decades, and then beats China.

As for Russia, not a single Eastern country had been able to face Western powers in a modern war and win.7 Not one! Westerners had steamrolled every other country, including India and the neighboring mighty China. Then along comes a random chain of islands at the edge of the Pacific, and it beats the behemothic Russia, which controlled an empire that extended from Europe to the Pacific. Extraordinary.

So how does all this tie to Japan’s three main geopolitical priorities?

1. Maintain internal unity

2. Control the islands that lead into Japan

3. Fend off rivals on the Asian continent

Japan’s Imperialism

When the Meiji Restoration begins, Japan starts wondering: To what extent can we keep our homeland united (objective 1) if we don’t control the roads that lead to it (objective 2)?

They concluded that they had to take control of all the paths to Japan. It wasn’t an overnight decision: They started with a few nearby islands. But the logic had no end: The more they took, the more buffer they thought they needed. The timeline is:

• 1853–1854: Commodore Perry enters Edo Bay

• 1868–1869: The Tokugawa Shogunate ends, the Meiji Restoration begins

• 1869: The Japanese take full control of Hokkaido and colonize it

• 1872–1879: They take over the Ryukyu island arc (it used to be a kingdom!)

• 1875: Russia concedes the Kuril islands, in exchange for recognizing Sakhalin island as Russian

• 1876: Japan forces Korea to open up trade with them, the same way Perry forced Japan to trade with the West

• 1894–1895: They go to war with China in the first Sino-Japanese War. They take Taiwan and push China out of Korea.

• 1900: Japan joins Western powers in fighting China during the anti-Western Boxer Rebellion.

• 1904–1905: War with Russia. The Japanese take southern Sakhalin and Russia's lease on the tip of the Liaodong Peninsula, just north of Korea.

• 1910: Korea is annexed.

• 1914–1919: During WW1, Japan joins the Allies to seize Germany’s colonies in the east: its Pacific islands and Chinese concessions.

• 1931: Japan invades the Chinese province of Manchuria, near Korea.

• 1937–1945: 2^nd Sino-Japanese War. Japan takes a bunch of territory in China.

Now we’re going to take a pause, because something subtle changes here that reveals Japan’s 4^th and last geopolitical goal.

Japan’s 4^th Geostrategic Goal: Resources

If you’ve followed up till now, you recognize exactly the problem here. One of these territories is unlike the others.

Controlling all the islands that lead to Japan is one thing. It’s an entirely different thing to take on the continent. The peninsula of Korea, you can maybe justify: It’s close enough to Japan and secluded enough from Asia. But that’s the slippery slope right there, and the Japanese knew it. If you take Korea, you are exposed to Manchuria. So you take it. And that exposes Manchuria to Mongolia, Russia, and China, so you try to get them, too. Japan gets locked into a catastrophic confrontation with not one, but two land empires (it goes to war with Russia and the USSR a couple of times, too), which it can’t win. Big mistake.

Since Japan can’t conquer China outright, it tries something different: Strangling it by taking French Indochina (Vietnam, Laos, Cambodia) in ~1940 to cut land supply routes to China.

Now let’s zoom out for a minute here. WW2 is now underway. France and the UK have declared war with the expansionist Germany, which is allied with similarly-expansionist Japan. Both are conquering land at breakneck speed. The US sees this and concludes:

• Japan is about to take the Malacca Strait to stop Chinese maritime supplies.

• The Philippines are right there, close to Japan. They might well take them.

• Japan is like Nazi Germany in Asia: If we let them continue, they will continue taking over lands until they split the world between them.

So the US does what it can to kneecap Japan: It stops selling it oil. Since 80% of Japan’s oil came from the US, this effectively meant losing the war. Japan could not operate without oil.

You can see the slippery slope from Korea, to China, to Indochina, to oil. It’s now forced to either abandon China—and acknowledge it f***ed up and wasted thousands of Japanese lives for an impossible goal—or keep going, which meant taking the Strait of Malacca (British) to control trade, and Indonesia (Dutch East Indies, a Dutch colony) to take its oil. But Japan knew the US wouldn’t like this and might enter the war.

So it decided to preemptively bomb the US’s navy in Hawaii, at Pearl Harbor.

Immediately after that, it took what are today the Philippines (US colony at the time), Malaysia (UK colony), and Indonesia (Dutch colony), allied with Thailand, and fought the British in Burma. This is how they got to this point:

If you have been following my GeoHistory articles, you know this is a nightmare of an empire. You need a massive navy to oppose two global powers (the US and the British), and an army to oppose three land ones (the Russians, the Chinese, and the British), along with guerilla wars from dozens of different nations.

Japan reached the end of the slide and fell into the mud.

Of course, the US proceeded to beat the s**t out of Japan, because Japan is a series of tiny islands while the US is a continent. And all because of the 4^th geopolitical priority: resources.

Japan was small, but had a huge industrialized population and economy. It couldn’t produce everything it needed, so it had to take it from abroad—and prevent its enemies from getting the same resources.

This is why Japan invaded Southeast Asia: to cut China’s resource supplies.
This is why Japan attacked the US: to secure oil.
And this is why the US followed the Pacific strategy it did.

The US didn’t need to conquer every tiny island. It just needed to break the network. Stop the resupplies, and you neutralize every island.

This is why the US invested heavily in a navy here, why its submarines focused on destroying the Japanese merchant fleet (resources!), and why it bypassed countless Japanese islands full of soldiers who were left useless and stranded.8 It only took enough islands (like the Philippines, Iwo Jima, Guam, and Okinawa) to build bases to control the areas and fly over Japan to drop bombs.

By 1945, Japan was out of oil and food. Its navy could not operate. Its population was starving. But it was also pretty fundamentalist. It was never going to give in to foreigners and was ready to fight to the death, literally sending women civilians to fight the enemy with bamboo spears if that’s what it took.

The US would have lost potentially millions of soldiers conquering Japan. That’s precisely what Japan wanted: Not to lose millions of people, but to make the invasion so costly to the US that they would force a settlement, with better peace terms for Japan.

That’s why the US dropped nuclear bombs on Hiroshima and Nagasaki instead. For the 2nd time in one century, the US forced Japan to realize its technological inferiority and fold.

How Japan’s 4 Geopolitical Priorities Drove Its History

So in summary, now you know how Japan’s geography determined its four geopolitical priorities, and how these have driven its history.

Goal 1: Unite the Main Islands

Because Japan is a series of big connected islands, but with flat valleys separated by mountains, it wants to be united, but it can’t easily do that. So Japan’s unity took about 2000 years, from 300 BC when the first Yayoi arrived, to 1600 AD, when Hideyoshi and Tokugawa finally united Japan. In the middle, they had a first attempt around 700 AD, but it was too early and it fell apart. The conditions were only right in 1600, and today, this goal has been fully achieved.

Goal 2: Control the Five Gates to Japan

This only started being important when foreigners from overseas started bothering Japan. The five gates are the Ryukyu Arc ending in Taiwan, the Izu-Bonin Arc, the Kuril Islands, Sakhalin Island, and Korea.

• The Izu-Bonin Arc is fully achieved (except Guam, but the US is an ally).

• The Ryukyu Arc and Taiwan were taken over at the end of the 1800s. Today, Taiwan is not Japan anymore, but it’s an ally via the US. Threatening Taiwan threatens Japan through the Ryukyu Arc, so it has a vested interest in protecting it from China.

• The Kuril Islands and Sakhalin were far north. Even Hokkaido is. So it took until the 1800s for Japan to fully take control of Hokkaido, and several conflicts with Russia to decide who owns the others. Right now, it’s Russia, but that might change in the future. They haven’t signed a peace treaty because of that.

• Korea: Japan invaded three times, and succeeded only once. This is a massive slippery slope for Japan, so I doubt it will try again. Better to have an ally there, so South Korea is super important for Japan.

Goal 3: Neutralize the Big Continental and Oceanic Powers

In the past, Japan tried to do this through war:

• Two Sino-Japanese wars, in the late 1800s and 1930s-40s

• The Russo-Japanese War in 1904-05, and WW2

• The war with the US in WW2

Very very bad idea. Japan is too small to be a comparable superpower. So it must ally with these powers instead. Today, it’s a US ally, so the ocean is covered. The instability of its relationship with its Russian and Chinese neighbors is very worrisome, and that becomes Japan’s main unachieved goal: How to ensure peace with them (or ensure their relative weakness).

Russia is weak today, that is good for Japan. In fact, bogging it down in the Ukrainian front is useful: While Russia focuses its attention and resources there, it can’t bother on the other side.

So Japan’s main concern is China. In the last few decades, Japan tried to become friends via trade, but it has learned (like the US), that China takes advantage of this to increase its power and might abuse it, so it’s become more cautious.

China’s crazy appendage, North Korea, is even more worrying, especially now that it has nuclear weapons. So Japan must manage it.

One thing few people know is that Japan is always only months away from developing a nuclear weapon. That’s their trump card.

Goal 4: Secure Resource Supplies through the Sea

Either to achieve Goal 3 (prevent its enemies from getting supplies) or for itself. It tried the war path, and that did not go well. It then tried the trade path, and that has worked extremely well. Japan can get everything through shipping and has established commercial ties and investments across all of Southeast Asia, which allows it to obtain everything it needs.

In summary, for Japan, the future of its geopolitics means remaining friends with the US, making sure it’s strong, containing North Korea, and managing China so that it never again becomes the threatening behemoth next door, and all of it can be seen from its geography.

In the next few articles on Japan, we’re going to answer a lot of fascinating questions on the country:

• How did Japan redraw the map of Asia?

• Why was it the only non-Western country that built an empire during the Industrial Revolution?

• How did it become the 2^nd richest country on Earth?

• Why has it stagnated in the last three decades?

• Why is it so indebted, but pays so little in interest?

• Why is it one of the first countries to shrink its population due to a lack of children?

• Why was Kyoto the capital at one point?

2026-09-27 09:42:20

If you know how to look at this map, you can deduce a lot of Japan’s history, why it has the borders it has today, where they are contested, and why it went through the wars it did.

What can you see?

The Four Main Islands

The three big islands of Honshu, Kyushu, and Shikoku were destined to be a political unit:

• They are very close to each other

• They’re also oriented mostly east–west. That means they share the same climate, which facilitates movement, because people’s lifestyle and crops don’t change.

Hokkaido is much farther north, which means different climate and ways of life, so unifying with the other islands would be harder. But the island is so close (~19 km, 12 mi) to Honshu that it was very likely to ultimately unify with Japan. All this explains a lot of Japanese history, like for example, why the three southern islands of Japan united partially for the first time over a thousand years ago, and why Hokkaido was only fully conquered and colonized at the end of the 1800s.

These four islands are not isolated in the middle of an ocean. There are five paths to reach them.

The Five Gates to Japan

1. Izu-Bonin Arc

The Izu-Bonin Arc goes nowhere in the Pacific, so it was logical that Japan would own it. This is where the islands of Guam and Iwo Jima are,1 which the US used to approach Japan from the south during WW2. The US still owns Guam.

The other four gates extend close enough to the continent that their ownership could be contested between Japan and the Asian powers.

2. Ryukyu & Taiwan

The Ryukyu arc ends at Taiwan, which is 130 km (80 mi) away from mainland China, separated by treacherous waters. Since Asia is such a massive continent, wars between its biggest powers have always been land-based, so their armies have also been land-based, and hence their navies were never strong. That’s why Taiwan has been part of the Netherlands (sea power), Spain (sea power), the Koxinga regime (a Chinese sea power), Japan (sea power), independent for the last 80 years (supported by the US, a sea power), and only part of China (Qing Dynasty) for a bit over 200 years, in the 1700s-1800s.

That explains why Taiwan has been contested throughout history, and after they lost their independence, the islands in the Ryukyu Arc have been part of either Japan or the ruling power in Taiwan. Since Taiwan has never been that strong, most of that arc of islands belongs to Japan today, after it conquered it in the late 1800s. This is why Okinawa, for example, belongs to Japan today.

As China’s economy and influence grows and it tries to return Taiwan to the fold, it includes more than just Taiwan in its claims. The most notorious example is the Senkaku Islands, whose exclusive economic zone might include oil, and are closest to China (of all the Japanese islands in the area).2

Notably, today China is encircled by enemies in the sea, which means they could blockade it. That’s why it is being so aggressive in pushing against its neighbors in the South China Sea, and another reason why it’s aggressive towards Taiwan.

3. Kuril Arc & 4. Sakhalin Island

The island of Sakhalin and the Kuril Arc could have belonged either to Japan or to the continental power in the region—which happens to be Russia. This has always depended on the winner of the latest war. Since Russia became an imperial power before Japan, it had time to reach the Pacific and take Sakhalin before Japan did. By that time, Japan had industrialized, and it won the war with Russia in 1904-1905, so it took control of the southern half of Sakhalin Island and the parts of the Kuril Arc it didn’t already cotrol. But then Japan lost WW2 in 1945, and the USSR rushed to reclaim as much of these islands as it could. It recovered Sakhalin and conquered all the the Kuril Islands

The USSR pushed so aggressively that the closest Russian island to Hokkaido is just ~2 mi / 4 km away!

Historically, Japan is in a stronger position than Russia to control the Kuril Islands, because they’re small distant islands and Japan is a maritime power, while Russia, by nature, is a land-based one. It’s very telling that Russia and Japan have never signed a peace treaty since WW2, mainly because Japan has a very strong historical claim to these islands, and they disagree on where exactly the border should be.

Russia kind of agrees that the small islands are Japanese (Habomai, Shikotan), but doesn’t want to give them up unless Japan ends the claim on the bigger Kunashir and Iturup.

In the other direction however, Sakhalin is big enough and close enough to the continent (less than 10 km) that, although it could have gone either way, it favored Russia historically—and has almost always been Russian.

5. Korea

Korea is far enough from Japan that it’s quite hard for either Japan to conquer Korea (three attempts, one succeeded in the late 1800s/early 1900s, for less than a century), or for Korea to conquer Japan (two attempts, failed, by the Mongols).

If Korea had been a flatland better connected to China, it would historically have been part of China. Being a mountainous peninsula, it has always been hard for China to control. Here’s a diagram, from the Korea article:

The result is that, for Japan, Korea is likely to always be a buffer against continental powers.

In between the two is the island of Tsushima, which could be used as a stepping stone in either direction, especially since it’s closer to Korea (~50 km) than to Japan (~130 km). The claim to it could have gone either way, but for the same reasons as before, it’s Japanese, since Korea has had to be a land power to fend off China, but Japan is a sea power with no threat to the south or east. It could focus on the island and get it.

Jeju Island, meanwhile, is closer to Korea via plenty of small islands, and farther from Japan, so it ended up in the Korean sphere.

The distance between Korea and Japan is long enough that there have been few invasions on either side, and even fewer that succeeded, but short enough that trade and technology could travel—mostly from the continent to Japan.

Resources

We’ve identified Japan’s first three main objectives:

1. Internal priority: Unify the four main islands

2. External priorities:

   1. Secure all the islands that lead to Japan

   2. Fend off the threats from powerful Asian empires

To figure out the last objective, we need to zoom back out.

Japan is lonely. There’s nothing to its east and south. To its north, there’s just cold. All its potential threats come from the west—but that’s also where all the resources used to come from.

Because Japan is resource poor. As it’s on a “newly” formed geology,3 it doesn’t have much oil or coal.4 The newly-formed mountains had gold, silver, and copper—which the country used extensively in its past—but not much more than that.5 All the rare-earth minerals, and even more common ones like iron, which it needs for its advanced technology, must be imported.6 And the valleys are good for agriculture, but the population has outgrown its production capacity, so it needs to import the majority of its food: 63% of its calories and 34% of its value.7

So Japan must procure lots of commodities from abroad. As an island, these commodities will always arrive by sea, so Japan must make sure it can secure its maritime supplies—whether by controlling them or by being friends with the ones who do. Most of Japan’s missteps leading to WW2 can be traced back to this.

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Japan’s 4 Geopolitical Objectives

So these are Japan’s 4 main geopolitical objectives:

1. Unite the four main islands

2. Secure the five gates that lead to Japan

3. Neutralize the superpowers that can invade: the Asian land powers and the international sea powers

4. Secure all the resources it needs through maritime trade

If you understand this, you can understand virtually all of Japan’s history:

• How it coalesced around 700 AD into a united country for 1000 years

• How it devolved into a feudal country over the centuries

• Why it was unified around 1600

• Why it forgot how to produce guns

• Why its samurais forgot how to use their katanas and their horses

• Why it closed down for 250 years

• Why it got traumatized in the mid-1800s

• Why it became the only non-Western country to industrialize in the 1800s

• Why it created its own empire in Asia

• Why it later lost it

• Why it is the way it is today

2026-09-23 18:35:34

Last week's premium article: What’s the Value of a Life?

With 37M people, Tokyo is the most populated city on Earth.

It would take you about five days to walk from one side to the other.

Since it’s so big, more than half of those nearly 40M people take the subway every day, which is why Tokyo’s railway network is the biggest and busiest in the world.1 Shinjuku is the busiest railway station in the world (nearly 4M people daily at its peak). Shibuya is the busiest pedestrian crossing (~100k people per hour during rush hour). Tokyo built a gigantic underground river to protect the city from flooding, sometimes referred to as the world’s largest drain. It has the most Michelin-starred restaurants, the largest wholesale fish market, one of the world’s busiest airports…

Why here though?

Isn’t there a better place?

Why did you pick the “big volcano place” for your capital, Japan?

Why is it also the capital of earthquakeland? Couldn’t you find a better place, seriously?

To add to the conundrum, Tokyo contains 30% of Japan’s population, yet it has been the capital of Japan for less than 200 years, and had just ~60k people around 1600! Yet by 1700, it might already have been the biggest city in the world!

So how come the biggest city in the world has been the capital for less than 200 years, and is situated in volcano, earthquake, tsunami, typhoon land?

It is not a coincidence! It’s there because of these things!

Japan Is Dense

Tokyo is populated because it’s in Japan, and Japan is very populated, as I explained in the previous article:

1. Japan’s staple is rice, which has a unique feature: It produces a lot of calories per km². It can feed a lot of people.

2. The south of Japan has a climate that allows for double cropping—one summer harvest of rice, one spring harvest of wheat or barley. So the population density is very high in the south.

3. Japan could supplement its diet with plenty of fish thanks to hot and cold currents meeting at the northeast coast of the main island, Honshu, producing a lot of seafood.

4. It was isolated enough that it didn’t have to fight constant wars, and it didn’t suffer wave after wave of infectious diseases.

5. It was small enough that most of its populated areas could be unified, reducing civil wars and the deaths associated with them.

6. The ashes from volcanic activity might have improved the fertility of the land.

7. The constant rain on mountains meant lots of sediments flowing to the plains, which fertilized them.

This is why every inch of Japan’s valleys is packed with people—especially in the south:

Tokyo’s Density

So the question becomes: Why is Tokyo the biggest of the Japanese cities?

The total population of a city depends on how much land it occupies, and how much population density there is in that land (people per km² x number of km²). Surprisingly, Tokyo’s population density is similar to those of Nagoya or Osaka! Since Tokyo contains ~30% of the country’s population, it implies it’s just 2.5x more dense than the average Japanese plain—which makes sense since it’s the capital. Sure, Tokyo’s central neighborhoods are denser, but some Osaka neighborhoods are in the same order of magnitude.

Tokyo is not even in the Top 50 of the world’s densest cities!2

So yes, Tokyo is quite dense, but not crazy dense. If not density then, Tokyo must just have a really big surface area. And indeed, what makes Tokyo so populated is that it has ~15,000 km² of high-density land. That’s why it takes 5 days to walk from one side to the other.

Why is Tokyo so extensive?

The Kanto Capital

A topographic map immediately shows the answer:

Tokyo is on the Kanto Plain, by far the biggest in Japan, accounting for ~15-20% of the historical farmland in the country.3 This meant that historically, it produced the most food, so its population could grow the most. And grow it did, until it became the most populated city in Japan.

OK so we now know why Japan is so populated, and why Tokyo is the biggest city within Japan (because it’s on the biggest plain). But then… Why is the biggest plain in the country there and not elsewhere in Japan? Why not in Nagoya, or Kyoto? As far as I know, nobody has answered that yet. So here is, for the first time, my hypothesis.

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2026-09-16 20:01:54

This week's premium article: What’s the Value of a Life?

I just enabled translations in a dozen other languages! If you read this article on web or the Substack app, you should see an option to change the language of this article. Use this and tell me what you think!

Japan is so weird:

• Not too long ago, it was one of the most populated countries on Earth. Why?

• That’s despite being quite small and mountainous. How come?

• Why is its capital one of the largest cities on Earth?

• How come it’s farther north, south, east, and west than South Korea?

• It’s much bigger than people think. How come?

• Why are its north and west coasts much less populated than the south and east?

• Why is the Russian island of Sakhalin, just north of Japan, so sparsely populated in comparison?

• Why does it have such a strong fishing culture?

• Why is most of its population of the same ethnic background, except for the people from the northern island of Hokkaido?

All of these questions have one single root cause, and it can be represented by sushi.

Japan’s Population

Japan is still the 12th most populated country in the world.

Of the top 50, it’s the 5^th most densely populated.

Why is it so densely populated?

It can only be due to food supply: Historically, the more food you could make, the more children would survive, and the more the population would grow, up to its maximum capacity. That’s a Malthusian world.

And since most food comes from farming, only countries with lots of farming could produce big populations. So if Japan is so populous, maybe it has lots of fertile land?

Or maybe Japan’s food comes from elsewhere? Maybe they import it? Or maybe it comes from the sea?

If it’s due to farming, why such a high yield? Is its land extremely fertile, like in Egypt or Java? If so, why? Or have the Japanese made the most of their fields—are they better farmers than those in other countries?

Or is it the politics? Did the Japanese organize in a way that maximized food production?

Or is it a matter of timing—the Japanese entered the Industrial Revolution early, so they were able to produce more food earlier on, therefore growing its population earlier than others?

Or maybe Japan is not good at growing people—it’s just good at keeping them alive? Maybe Japan, as an island, avoided most wars that plagued other countries, so it didn’t lose that much population to war?

Which one is it? Maybe volcanoes?

Japan vs Java

If you read Why Is Java so Weird?, you know that this island is packed with people because of its volcanoes.

Is this also the reason for Japan’s huge population? It’s possible: They’re both on the Ring of Fire, the string of volcanoes and earthquakes-prone regions around the Pacific Ocean, which extends partway into the Indian Ocean.

To this day, new islands are constantly being formed in Japan!

This is near Iwo Jima. Source: Kazuhiro Ichikawa, via Massimo (@Rainmaker1973)

The Ring of Fire is very obvious on Google Maps: When you see the underwater trenches and mountain ranges on the edge of the tectonic plates, you realize that Japan is simply the part that emerges from the water—just like the Philippines and Taiwan!

This is also why Japan is much bigger than people think: It has many islands on these subsea mountain ranges:

This is why Japan claims these territorial waters:

Japan’s exclusive economic zone is the 8^th biggest in the world thanks to all these islands.

All these islands are the reason why the US famously took the islands of Iwo Jima and Okinawa during WW2: The US needed pit stops between Hawaii and Japan, and these islands were remote enough from the main islands that they were relatively easy to overcome, but they were also close enough to give access to Japan’s four big islands, and the conquest severed the connection between Japan and its colonies in the Pacific.

Japan eventually got them back, and that's why its maritime boundaries are farther north, south, east, and west vs South Korea.

The tectonic plates also explain why Japan is so mountainous:

Only 12% of Japan’s land is arable! So is this rare land extremely fertile because its volcanic ash fertilizes the soils, just like on Java?

Big surprise! Japan today is actually not as densely populated as South Korea or Taiwan, if we consider total cultivated land! And South Korea is not a volcanic peninsula! So, in the case of Japan, its large population isn’t attributable to volcanoes. So what is it, then? Well, let’s see where the Japanese people actually live.

Japan’s Food Geography

Half of Japan’s population lives here. Why?

Here’s a full population density map:

Here’s a clue:

Do you see it already?

These valleys surrounded by mountains make up the 12% of arable land. It’s obvious from maps like this one, showing how every nook and cranny is full of human habitats.

But also, you can see in the previous map that the big urban areas are in the southern valleys. There are other big valleys to the north, but those don’t harbor such big populations. Why?

Notice the black line. Historically, below it, farmers would plant rice in May / June and harvest it September / October, when they would drain the rice paddies and plant wheat or barley, to harvest just before planting the rice again.

Did this really have such an enormous impact on Japan’s population? If so, we should see two things. First, the amount land that rice needs to generate some amount of calories should be very small. It is:

Second, we should see the Japanese population grow when rice gets introduced, and then again when double cropping starts, and these must happen in Japan before they happen elsewhere. Do we see that?

This is the population of different East and Southeast Asian countries over the last 2,000 years:

Japan’s population was bigger than its neighbors’ for nearly 1,500 years. Let’s zoom in on that, eliminating the hypergrowth of the 20^th century:

Indonesia’s population was probably larger than Japan’s early on, but around the first century, Japan’s population started growing much faster than any neighboring country’s. It slowed down around 700-900 AD, picked up its growth again ~1200 CE, stopped in its tracks in the early 1700s, and exploded again in the 1800s. It only stopped growing recently, with the demographic collapse post-2000. We can see clearly Japan’s three big growth spurts in this graph:

The first growth spurt lasted until 700 AD, and was the result of the introduction of wet rice agriculture in Japan, via China and then Korea.

Japan is naturally quite fertile, because the rain that flows down from so many mountains brings with it not just water, but sediments to fertilize the land.

Archaeologists believe the Jōmon people arrived on the island about 40k years ago, but in the first millennium BC, the Yayoi started immigrating into Japan from Korea, bringing with them first rice paddy technology, and eventually iron tech, which helped increase agricultural productivity. That’s why the average Japanese today is genetically very close to Koreans.

Over the centuries, as the population grew, it moved farther north, bringing with it its farming knowledge.

That’s why the population boomed: It expanded along with the share of farmed land, and its productivity.

The Population Slowdown

Alas, the boom did not last forever: The population went from ~6M in 700 AD to ~4M in 1150 AD.

By around 700 AD, the Japanese had converted the best valleys into farmland, and the speed of conversion began to slow down and focus on marginal land—not the most fertile. Growth stalled. The adoption of new farming techniques like the use of iron slowed down, too.

Japan’s East-West vs North-South

This is one reason why Hokkaido, the northern island, reflects the original native population on the genetic map more than the rest of Japan (the Ainu, and also local mixing): Rice cultivation did make it there, but it was later abandoned as it was not as effective. The farmers from the south went as far as their rice agriculture allowed.

Why didn’t rice travel farther north?

Notice how a warm current from the Philippines and Taiwan reaches all the way to Japan, warming it up.1 But also, it meets a cold northern current around the north of the Honshu island. These currents are called Kuroshio and Orashio:

North of that point, it was too cold for rice cultivation.

However, the names of these currents tell us something else about Japan’s food: Kuroshio means “black current”, because this water is devoid of nutrients, so it’s more transparent. Meanwhile, Oyashio means “parent current”, because it comes from the north full of nutrients, bringing plenty of fish—the source of the fishing culture in Japan.

And this is why sushi is the most Japanese type of food. It’s where rice meets fish: the rice from the continent, migrating from south to north through the islands, and increasing the population through rice farming in the Japanese plains; the fish from the ocean, with the nutrients moving from north to south, following the winds and currents.

North & South. The rice is packed, just like the Japanese

Indeed, winds follow the same pattern as currents: Winds from Siberia travel over the Sea of Japan, catch a lot of moisture from this sea, and the drop it as they reach the tall Japanese mountains. This is why Japan’s peaks can get serious snowfall.

Why was rice pushed so far north? Because that was Japan’s staple, and that meant taxes were frequently collected in rice, which meant rulers had a strong incentive to push for rice production at the expense of other crops. Alas, the north simply couldn’t produce it.

It’s not a coincidence, then, that the southern half of Japan is more populated: Because it runs east-west, most of these islands share a similar climate, and they all could share the same crops and similar lifestyles. But then Japan bends northwards, and the islands start changing climates much faster. We can see it in the climate map of Japan:

Or, geometrically, through this map:

This is why agriculture was so crucial for Japan’s population growth—and why it stalled once most of the arable valleys were converted to rice cultivation.

But the increase in population density made for easier spread of diseases. Between 700 and 1200 AD, several waves of infectious diseases, including smallpox and measles, decimated the country, and that stalled its growth too. Why didn’t these diseases hit before? Because Japan, as an island nation, was isolated enough that most diseases didn’t make it there until maritime trade became common.

Back to Growth

Japan’s growth picks up again around 1200 AD, when new agricultural techniques are introduced into the country from the continent. First, the double cropping we mentioned before, but not because it doubled the calories produced (it didn’t: rice produces more calories per km² than wheat or barley), but rather because it added more calories at exactly the time of most need,2 it diversified the food, and it diversified the risk: Maybe the summer harvest was bad, but the winter one was good.

There’s another reason why growth was so vertiginous: unity.

Japanese Unity

Japan united very early.

By the Nara Period, around 700 AD, the biggest population centers already belonged to one single polity. By 1100 AD, the three southern islands of Honshu, Kyushu, and Shikoku were united. This meant Japan has had considerably fewer wars than most other countries. Even its long period of warring states (Sengoku Period), which lasted ~150 years between ~1450 and 1600, did not cause a dramatic loss of population.

This unity and relative lack of wars prevented massive deaths from conflict and from disease, and allowed the Japanese to invest in their irrigation infrastructure, which increased the fertility of existing fields, and also increased the surface of farming fields by reclamation of river floodplains.

Why so much unity? Geography, of course.

Geographic Seclusion

Japan is separated from the Asian continent by two seas that hinder access. The easiest path is through Korea, but the Korean Strait is quite wide (~200 km, or ~120 mi), 5x wider than the distance between France and England. And the Kuroshio current makes it very hard to cross. That said, the island of Tsushima is just in the middle, serving as a stepping stone. The Mongols tried to invade Japan twice, and both times they reached Tsushima. They were vanquished by typhoons both times—although the second time they did reach the main Japanese shores and were beaten back by the Japanese.3

The key is why only twice? Because the Korean Peninsula was a perfect buffer: Since China is a massive fertile valley surrounded by peoples from other parts of Asia, it could never fully focus on the Korean Peninsula, and as a result, Korea remained pretty independent. The Koreans fought all the wars against China on behalf of the Japanese.

And why is there a sea between China and Korea on one side, and Japan on the other? Because it’s a back-arc basin:

As the Pacific Plate dives below the Asian Plate, it creates a mountain ridge with volcanoes, which is Japan. But it also pulls Japan towards the Pacific. Imagine you’re pulling a tablecloth downward: the cloth on the table will move towards the edge. That’s what’s happening with Japan, and as a result a hole forms between Japan and Asia and fills with seawater.

This also explains why Japan’s fertile valleys are where they are:

See how much shallow sea there is around Japan? That’s ancient crust from Asia. Over millions of years, sediments coming from the mountains accumulated there, creating the alluvial valleys that are so fertile today. Compare that map with this one of population density:

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Takeaways

So here’s how so many aspects of Japan are explained by one factor: its geology.

• It makes it a very mountainous country: It’s the emerged side of the mountain ridge formed by the collision between the Pacific and Asian tectonic plates.

• It’s also why Japan’s maritime territory is so huge: It owns plenty of islands at the tip of these ridges.

• The collision between these plates is why Japan is close to Asia’s mainland, but not on it: It split Japan from Asia due to the formation of a back-arc basin, which is today the Sea of Japan and the East China Sea.

• This is why the sea around the Japanese main islands is pretty flat: It’s old continental shelf. As sediment accumulated from the mountains, it filled the sea, creating very fertile alluvial valleys.

• These are the valleys that produce most of the food, which is why Japan’s population is so concentrated in these valleys.

• The seas also isolated Japan enough that it didn’t suffer too many invasions and could remain united for a very long time, thus avoiding war deaths and facilitating investment in irrigation infrastructure, both of which increased its population.

• But also, Japan remained close enough to the continent to access crucial innovations, including rice cultivation, double cropping, and iron tools.

• The rice could be cultivated because the country is warm enough—despite being reasonably far north—thanks to the winds and sea currents that come from the warmer Philippines. The geographical limit where warm and cold currents collide is also the limit of historic rice cultivation.

• That’s why the vast majority of Japan’s population is concentrated in the southern parts of the country, why the north took much longer to be conquered, why today Hokkaido retains much more Jomon/Ainu ancestry than the rest of Japan, and why the Russian island of Sakhalin is so sparsely populated in comparison: The islands lie east-west in the south, and rice cultivation and the rest of Japanese lifestyle could be shared throughout these regions. Japan’s Honshu island then bends northwards together with the Pacific-Asian plate border, and the climate gets cold really fast. Hokkaido was too remote and cold for consistent rice harvests or double cropping. Sakhalin is even worse.

• This is also why Japan’s historical population booms followed the introduction of agricultural techniques: First, with rice agriculture and iron tools, then stopping when most of the available land was exhausted. Later, the introduction of further innovations such as double cropping and agricultural irrigation to reclaim floodplains increased both the amount of farmland and its productivity.

• Rice was also one way the country remained united, as it could use rice as currency for taxation.

• The downside of absorbing these technologies from the mainland was the consequent waves of disease, which were the other main obstacle to population growth. As Japan became more densely populated, infections circulated faster.

• The sea currents are why Japan has such a fishing culture: The north and south sea currents meet in northern Honshu, bringing plenty of nutrients to the warm waters and cultivating life.4

• Volcanoes might have had a small contribution to the fertility of the land, but they’re probably not a key factor.

In summary, Japan became so populous despite its small land because it could produce a lot of food from a small amount of usable land, while losing relatively few people and productive assets to war.

And sushi is the best way to represent all this, as rice came from the south, fish comes from the northern currents, and they bring the two elements that make up Japan: its sea and its land.

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