単一民族という神話：縄文・弥生・古墳の多数派The Myth of a Single People: Jomon, Yayoi, and the Kofun Majority

The formidable barrier we face when looking at history is the monolithic worldview carried by each of us as individuals living in futures shaped by a form of nationalism. Within the limited scope of East Asia this means the closed historical perspectives of China, Korea, North Korea, and Japan, each of which continues to exert an ideological influence whenever we attempt to think about history. The result is that even now, in the mid-2020s, we remain trapped in the habit of viewing ancient history through the closed worldview of each nation's sense of its own uniqueness. Productive discussion does not take place, and the true image of antiquity is left as an unsolved mystery.

Yet as I continue fieldwork in my home country I find myself confronting the impossibility of drawing the history of Japan as a self-contained story of Japan. This is simultaneously the impossibility of drawing the history of China as a self-contained story of China, of Korea as Korea, of North Korea as North Korea. Inquiry conducted on the premise of these national spaces may carry modern ideological significance, but from the standpoint of history as a whole it is not the essence of the matter. The problem always comes down to the individual's attitude when confronted with this impossibility. Once you hold the will to see the history of your own country not as a point but as a surface, you are thrown into a struggle that oscillates between the monolithic national space and the place understood as a pluralistic world. And beyond that lies the movement of East Asia as a whole. Beyond that, the movement of the entire planet.

This inner struggle is something every person must pass through for as long as we remain stalled in modernity. It is something we must carry to the end. I believe it is only when each of us in the present takes up this challenge, setting it alongside but apart from the particular problems of our home countries, that the world will arrive at an era of integration in the truest sense. This is not about denying or despising or abstracting or diminishing one's homeland. The future lies not in dismantling the communal illusion but in transforming it through the united will of the people. For that to happen, the volume of problems that must be thought through in East Asia alone is enormous.

The broad arc of ancient Japanese history runs from the Paleolithic through the Jomon period, the Yayoi period, and into the Kofun period. Scholars disagree completely on when each era begins and ends, and the discrepancies sometimes span thousands of years, so I do not place great importance on exact boundaries. Even in the transition from Jomon to Yayoi, it is less a case of Yayoi people suddenly appearing than of a parent population that would become the Yayoi having flowed in over the course of several hundred to a thousand years before the conventional boundary. Through these eras Japan eventually enters the period of Buddhism's arrival via China.

Simply looking at this total history is enough to collapse one of the most widely promoted fabrications in the world, the myth that the Japanese are a single ethnic people. Last week I wrote about undergoing a cutting-edge genetic test in Tokyo. One of the distinctive features of this test is that it explicitly divides Japanese ancestry into Jomon, Yayoi, and Kofun layers and produces a ratio that makes visible which root a given individual derives from.

Japan as a whole still positions its national origins within the framework of a single ethnic people, and this understanding is shared internationally. But even when we speak of Japanese roots, at minimum three layers should be recognized: Jomon, Yayoi, and Kofun. These are peoples of different origins. The parent population from which the Jomon derived has not yet been identified, but they are estimated to have been a considerably independent group within East Asia. It has also been suggested that members of this group crossed to the Americas and Australia and became the origin of indigenous peoples there. The Yayoi, on the other hand, had their roots primarily near the West Liao River in northeast Asia. In civilizational terms they were the bearers of the Hongshan culture, but after climate change forced them to migrate, the groups that moved south passed through the Korean Peninsula to reach Japan while the groups that moved west reached as far as Scandinavia.

Interestingly, it had already been noted before the Second World War that Japanese mythology and Norse mythology share certain commonalities. At the time, because the West held dominant cultural prestige, it was assumed that the cultural influence had flowed from Scandinavia to Japan. The reality was that both possessed a common ancestor in northeast Asia. I personally see in Japandi, the fusion of Japanese and Scandinavian sensibilities, an echo of an ancient relationship in which common ancestors resonate across millennia.

From this vantage point it is self-evident that after the Yayoi flowed in as immigrants, a people fundamentally different from the Jomon were coexisting on the Japanese archipelago. Yet the single-ethnicity thesis still offers the inexplicable explanation that the Jomon became the Yayoi, and the view that the Yayoi were not immigrants retains considerable force. This framing is written into the standard displays at ethnographic museums, which gives it an appearance of solidity. But the denial of immigration in ancient Japan is meaningless and amounts to baseless superstition.

At the same time we must consider the possibility that the Jomon themselves were not a single ethnic group but were undergoing complex admixture. I believe there was a base population among the Jomon, but that complex intermixing occurred in certain regions. The people I have in mind as that base population came to the Japanese archipelago from the Southeast Asian side. The basis for this is the Kuroshio Current, a massive ocean current generated by strong winds blowing from the direction of Hawaii against the eastern side of the Philippine Islands near the equator. The Kuroshio flows into the East China Sea and runs northward along the Pacific coast of the Japanese archipelago as the largest ocean current in the world. A crucial caveat here is that we must also account for the fact that the Jomon were simultaneously using the Kuroshio to travel outward to Southeast Asia. There are accounts of fishing expeditions from the Japanese archipelago all the way to Australia that predate the eighteenth-century British settlement. These may trace back to ancient Jomon routes.

In fact, while much remains to be clarified, it has already been noted that genetic markers unique to the Jomon are related to the indigenous peoples of Taiwan, Australia, and elsewhere. Our instinct is to imagine the Japanese archipelago as the final destination to which people drifted, but unless we also consider the possibility that the Jomon crossed the sea in the opposite direction, the full picture will not come into focus. When we consider the possibility of large-scale Jomon migration across the ocean, many factors come into play. One that I focus on is the presence of subsequent immigrants. What deserves particular attention here is not so much the Yayoi, with their northeast Asian roots, as the group that arrived after them as immigrants. These are the Kofun people. The Kofun people have East Asian roots and are close to the modern Han Chinese, and the crucial fact is that the majority of present-day Japanese are their descendants.

On the chronological axis the sequence is Jomon, Yayoi, Kofun. Within the Japanese archipelago the Kofun people are the latest arrivals. Under the single-ethnicity thesis, the roots of the Japanese nation are framed as a natural development from Jomon to Yayoi with immigration acknowledged only marginally. The Kofun people are not treated as a separate group. Even now, thinking is based on two ancestral populations, Jomon and Yayoi. Recent genetic studies have clearly identified the Kofun people as a distinct parent population, but the single-ethnicity thesis ignores this. School education in Japan still teaches that Japanese roots lie in the Jomon and the Yayoi. The existence of the Kofun people is not taught.

The important point here is that Japan's single-ethnicity thesis is in fact confined to the lineage of the Kofun majority. The entity ideologically constructed as "the Japanese people" actually refers in a limited way to a population whose majority derives from the Kofun, an East Asian-rooted group. Earlier populations are excluded. This dynamic accelerated around the Meiji era and is typified by the assimilation policies directed at the Ainu of Hokkaido and the people of Okinawa.

The background was that these populations carried a significantly higher proportion of non-Kofun ancestry and were therefore not regarded as Japanese. That said, even the Ainu and Okinawans underwent historical admixture with the Kofun population. It is only the proportion that is lower. Furthermore, the Ainu are not an indigenous people unique to Japan in any simple sense. They are a group formed through highly complex admixture. The Jomon certainly form a base, but layered onto that are immigrant groups arriving via northern routes through Russia and migrant groups from the Japanese archipelago itself, among others. The Ainu are not equivalent to Jomon descendants, yet this point remains completely unappreciated. The absurd claim that the Ainu are Japan's indigenous people continues to be advanced. This framing of the Ainu as indigenous operates on exactly the same principle as the single-ethnicity thesis for the Japanese. The two are in fact two sides of the same coin. Both must be discarded.

The Okinawans, too, received strong influence from the geographical proximity of China, and on certain islands the lineage of East Asian immigrants is strikingly visible. In Okinawa's case, the Yaeyama Islands such as Ishigaki and Miyako are clearly distinct in ethnic composition from the Okinawa main island sphere. A monolithic Okinawan people does not exist either. The picture changes depending on where you look. A monolithic single-ethnicity thesis is impossible and a monolithic indigenous-people thesis is equally impossible. The same holds across the entire Japanese archipelago, excluding Hokkaido and Okinawa. We say Japan, but southern Kyushu and northern Kyushu are populated by people of entirely different ethnic profiles.

The reason the Kofun people, who constitute the majority of present-day Japanese ancestry, have not become clearly recognized is that no one yet knows with certainty how many arrived as immigrants. By the late twentieth century the existence of immigrants corresponding to the Kofun people had already been noted, but estimates of their numbers range from one million to a few hundred depending on the scholar. No one knows the reality. One intriguing point, however, is that horses were brought to Japan in the course of Kofun immigration. Wild horses are thought to have existed in Japan during the Paleolithic, but they went extinct around the beginning of the Jomon period and after that there were no horses on the archipelago. It was the Kofun people who brought them back in large numbers.

That said, even though the Kofun people are described as East Asian in origin, China is vast and composed of innumerable ethnic groups. Precise identification will have to await broader future research. The reason the single-ethnicity thesis appears to carry a degree of plausibility is probably that a crude understanding passes unchallenged, one based on the observation that many people happen to match the fabricated image of what a Japanese person looks like. From my experience traveling across Japan that impression strikes me as hopelessly simplistic, but it is the same dynamic by which I cannot clearly distinguish among Western Europeans and they cannot clearly distinguish among Asians. Everything appears the same. And it is precisely this crudeness that the ideology of the single-ethnicity thesis is powered by.