Name: Why Most Japanese Just Live In This Small Line
Uploaded: 2025-11-20T17:16:51.000Z
Duration: 23 min 47 s
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Japan is one of the world's most populous countries, home to around 123 million people.

Today, Japan is the world's 11th most populous country, and

it's also home to the world's second most populous island, Honshu, home to more than 83% of the Japanese population, to more than 102 million people all on its own.

But when you look just beneath the surface of these statistics, you'll see that Japan has one of the most unusual and interesting population patterns in the world.

Because the vast majority of Japan's population all just live within a relatively small and linear line that runs across the center and east of the country's south.

Nearly two thirds of the entire Japanese population all just live within this line that encompasses most of Japan's largest metropolitan areas, including Fukuoka, Hidekiyushu, Hiroshima, Okayama, Takamatsu, Kobe, Osaka, Kyoto, Nagoya, Hamamatsu, Shizuoka, and

Roughly 80 million Japanese live within this long but narrow line that extends for around 1,200 kilometers across, an area that only makes up less than 10% of Japan's total land area, leaving behind the remaining 90% of the country that's significantly more sparsely populated.

To help you visualize this divide better, roughly 80 million Japanese live within the line that makes up less than 10% of the country's area, while only about 43 million Japanese live within the rest of the 90% of the country, nearly half of the population lives within the much, much, much smaller line.

The line of Japan contains an average population density that's nearly 17 times greater than the rest of the country has, which is one of the most astonishing differences between two different regions of the same country seen anywhere in the world.

Put another way, the line of Japan all throughout is even more dense than the crowded city state of Vatican City is.

While the rest of Japan has an average population density that's about the same as the US State of Pennsylvania, economically, the line also accounts for an Even more astonishing 70% of the entire Japanese economy.

This highly populated and economically powerful line across Japan has been referred to by many different names.

Sometimes it's referred to as the Taihei Belt, which in English means Pacific Belt, and

I will continue referring to it from here on as the Taiheo Belt.

And in many ways, it is fairly comparable in both size and scope to the Northeast megalopolis in the United States, the most densely populated continuous urban area in North America.

That runs across the Cities of Washington, D.C. baltimore, Philadelphia, New York City, and Boston.

Geographically, the Taiheo Belt is a bit larger.

Placed side by side with Fukuoka beginning where Washington, D.C.

begins, the Taiheo Belt would extend across the entire northeast coast well beyond Boston, with Tokyo placed roughly in central Maine, with around 80 million people living across it.

The Taiheo Belt is also significantly more populated than the Northeast Megalopolis is as well, which is home to only about 53 million people by comparison.

This difference in population density and scale between the two partly explains the dramatically superior rail connectivity across the Taiheo Belt that exists today.

Japan's famous Shinkansen bullet train network connects the entire corridor together today and enables rapid transport from Tokyo to Fukuyama in only about three and a half hours, roughly half the time that it takes Amtrak's Acela to cover the same distance from Boston to Washington, D.C.

But all of this begs a fundamental why does Japan's human geography look like this in the first place?

Why does so much of Japan's population all live crammed together within a relatively narrow straight line across a small part of the country?

And why is the rest of the country so much more relatively empty by comparison?

First of all, it helps a lot to just simply look at a topographic map that shows Japan's elevation.

Japan is one of the most mountainous countries in the world, with about 73% of the country's total land area covered by them, leaving behind only about a quarter of the country left for significant human habitation in the few scattered areas of flatter land where urban development is easier and more affordable.

Since time immemorial, this fact has left the people of the Japanese archipelago restricted to living within close proximity to each other along the coastal plains and across the few flatter areas within the interior, where some stepped rice fields can be placed in the hills.

There are pockets of flat land found all across the country, from the west to the east and from the north to the south.

But you will note how the Taiheiyo Belt follows across what happens to be the three largest continuous areas of flat land found anywhere in the country, the Kenai Plain that encompasses the cities of Osaka, Kobe, and

Kyoto the Nobi Plain that encompasses Nagoya, and

the single largest plain of all that can be found anywhere in Japan, the Kanto Plain that encompasses the megacity of Tokyo.

All three of these plains also have large rivers that flow through them that make them ideal centers for agriculture and supporting large populations.

The Nagoya metropolitan area, crowded within the Nobi Plain, is Japan's third largest metro area, home to more than 9.3 million people.

The Osaka metropolitan area, crowded within the flat Kenai Plain, is the second largest, home to more than 19.3 million people.

While the Tokyo metropolitan area, crowded within the Kanto Plain, is the largest not only in Japan, but

in the entire world, with more than 41 million people living there today, more than double the population of the New York City metropolitan area in the United states.

Collectively, these three plains alone are home to nearly 70 million people.

Most of the population lives within the whole Taiheo Belt, and

indeed more than half of the entire nationwide population.

They've historically been the most major population economic and political centers in Japan for centuries now that have long dominated over the rest of the country.

But that's not just because they're the three largest areas of continuous flat land available for city building.

The western side of the island of Honju that faces the Sea of Japan has some areas of flat land around the coast too.

But on top of none of these areas being quite as large as the Kenai, Novi and Kanto Plains that are over on the Pacific side, they have multiple other disadvantages that have always made them less attractive places to settle in as well.

For one thing, the Pacific side of Japan, for whatever reason, was also blessed by the RNG geography gods with significantly larger, deeper and more useful natural harbors as well.

Almost miraculously, Japan is home to not one, but

two of the most incredible natural harbors that can be found anywhere on the planet that are simultaneously huge, deep, exceptionally well sheltered, and

directly connected to large flat hinterlands that can support huge adjacent population centers, Tokyo Bay and Osaka Bay, which of course are also directly connected to the huge flat Kanto and Kenai plains.

Tokyo Bay in particular, large, very deep, very well sheltered, and

surrounded by the flat Kanto Plain that's home to Tokyo with its 41 million people, is so comically overpowered from a commercial trade perspective that it alone handles around 350 million tons of seaborne cargo annually, which is comparable to the entire maritime trade volume of the whole of Italy combined.

While not quite as exceptional as the Tokyo and Osaka Bays are, the Ise Bay that connects directly to the Nobi Plain where Nagoya is concentrated, is also still world class, being huge, deep and fairly well sheltered, with the huge Nobi Plain directly adjacent.

Obviously, these three world class natural harbors that just so happen to directly connect to the three largest flat plains in the country made them even more obvious centers to settle in in order to capitalize on the ridiculous commercial trade and nav potentials.

The Pacific side of Japan has many other excellent natural harbors as well, including the Kagoshima and Nagasaki Bays on the Pacific facing side of Kyushu and Hiroshima Bay on Honshu.

The Western Sea of Japan facing side of Honshu, by comparison, is nowhere near as jagged as the Pacific facing side is.

as a result, it has nowhere near as useful of natural harbors and ports as the Pacific facing side has.

The only notable harbors on the Sea of Japan's side of Honshu are Meizuru Bay and the Porta Niigata.

But both of them are still just a tiny fraction of the size of the massive natural harbors over on the Pacific side, like the Tokyo and Osaka Bays, and

neither of them are connected to as large of a flat plain in the interior that can support millions of people nearby to sustain trade.

The Sea of Japan's side of Honshu and the entire northern island of Hokkaido simply have nowhere near as ideal natural harbors to utilize for trade and commerce.

On top of nowhere near as large of plains to build cities in.

Compounding other disadvantages, to support huge populations even further, and

to make the Pacific side of Japan even more advantageous, it also has the Sato Inland Sea, which is, without a coincidence, placed directly in the center of the Taihei Belt.

Because the vast majority of Japan's landmass is mountainous, the islands have an abundance of water.

But the dearth of flatland also means that nearly all of the rivers running through the interior are rough and full of rapids and waterfalls that make them completely unsuitable for interior navigation and trade, something that's made even worse by the fact that most of the rivers don't even connect together either.

But what Japan does have that more than makes up for the lack of navigable rivers is the Seido Inland Sea, the largely enclosed body of water that's protected from the rest of the Pacific between the main islands of Honshu, Kyushu, and

Between these main islands, there are only four very narrow straits that connect the Sado Inland Sea with the rest of the Greater Pacific, which makes its water significantly more calm than anywhere in the surrounding ocean.

While the tidal currents within the four narrow straits leading into and out of the sea can be strong and complex, the rest of the sea is exceptionally navigable, and

it blesses Japan's geography with one of the largest internal seas for navigation and trade that can be found anywhere in the world.

To give you just a sense of the Sado Wyland Sea's scale, if you placed it over the northeast coast of the United States.

It would stretch from Washington D.C. beyond New York City into southern Connecticut.

There's also around 700 separate smaller islands that can be found dotted all across the Sado Inland Sea as well, several of them complete with their own incredible deep natural harbors that provided abundant safe anchorage and stopovers for ships during storms, which made the whole body of water perfect for early maritime trade during the ancient and medieval eras.

The sea also provides a moderating effect on the regional climate around it, to the extent that it's often referred to as Japan's Mediterranean.

An area with year round warm temperatures that supports year round navigation and agriculture.

During pre industrial times in Japan, building roads across Japan's mountainous terrain to connect disparate flat areas together was extremely difficult.

But the calm waters of the Sado Inland Sea provided a critical alternative for much easier and efficient sea based transportation.

Instead, even better, at the eastern edge of the sea, the presence of Awaji island created the even further enclosed Osaka Bay within it directly connected to the huge flat area of the Kenai Plain in the interior.

Thus, from early on within Japan's history, the Seido Inland Sea became the critical maritime trade artery that connected the Kenai Plain and the Osaka Bay and all the other areas around its shorelines with a rest of Honshu to the east, including the Nobi and Kanto Plains with their own ideal harbors, and

with mainland Asia and Korea further to the west.

All of this huge trade volume flowing through it transformed the Seido Inland Sea into the wealthiest area of Japan for centuries, which encouraged settlement around it and which in particular directly contributed to the massive population growth in the Kenai Plain that gave rise to Japan's early political center in Kyoto and what eventually became the mega port city of Osaka.

For centuries, it was Osaka that was the economic epicenter of Japan.

by the time of the Tokugawa Shogunate, all of Japan's feudal lords known as Daimyo, had established an office in the city that were known as Ozakaya Shiki, which were among the earliest forms of banks in Japan, which further reinforced Osaka's early importance.

And by the time of the industrial age, the other cities around the Seido Inland Sea, like Kobe, Okayama, Takamatsu, Fukuyama, Hiroshima and Kita Kyushu, all developed into major industrial shipping and naval centers as well, carrying over the Seido Inland Sea's importance into the modern era and further solidifying the population concentration within what would become known as the Taihyo Belt that runs directly across it.

After the Tokugawa Shogunate managed to largely unify Japan in the early 17th century, the Shoguns decided to establish the seat of their power away from the historical Imperial capital at Kyoto, towards the east at Edo, within the larger Kanto Plan Plain.

One of the most profound impacts on Japan's human geography and population pattern that has ever happened.

The Shoguns relocated their administrative center to Edo, which would later be renamed to Tokyo, during the 19th century, in order to distance themselves from the Emperor and Japan's traditional nobility in Kyoto, so that they wouldn't be overshadowed by them.

While they also saw the potential for rapid urban development in the large and expansive Kanto Plain that was still fairly underdeveloped by the time of the early 17th century.

At that time, Edo was nothing but a small castle town that was probably only home to a few tens of thousands of people.

But within only a century of Tokugawa's Shogunate rule, with Edo as their de facto capital, by around 1700, its population had exploded to more than a million people, which transformed it from a small town into one of the largest cities in the world within only a couple of lifetimes.

Fueling this enormous growth of people in Edo and the Kanto Plain and elsewhere along the modern Taiheo Belt during the Tokugawa era was the Shogunate centuries long policy that was known as Sankenko Tai, which required all of Japan's feudal lords or daimyo, to alternate living between their domain and Edo every other year.

The hundreds of daimyo at any given time in Japan were forced by this policy to maintain a lavish residence both at their homes and in the Shogun's capital at Edo.

And every other year when the daimyo moved back and forth between them, they were forced to undergo expensive and lavish processions with their full entourages.

For the Shogun, the policy was a deliberate strategy to force the daimyos and their families into a state of surveillance in the capital.

While the extreme financial burden of maintaining lavish mansions in both locations and moving back and forth between them every other year was both time and money that they couldn't spend on plotting to overthrow the Shogun.

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