縄文人はどこから来たのかWhere Did the Jomon People Come From?

Recently I have been focusing intensively on preparing the detailed schedule for the research journey that will begin in September, as well as on matters that should be investigated in advance. Among these, the question I have pursued most over the past seven years is how the movements of the Jomon within the Japanese archipelago laid the foundation for a plural cultural ground that ultimately led to Japan today. To clarify this, as has long been suggested, it is necessary to examine the processes by which the ancestral groups who would later be called the Jomon entered the ancient Japanese archipelago via both northern and southern routes from the continent.

However, although research based on this assumption has been carried out for decades in various fields, it remains a major mystery with no clear conclusion. In essence, while it is generally accepted that people began settling in the Japanese archipelago through these two main routes, how this migration actually occurred is still unknown. Based on the topography of the time and lowered sea levels, it seems plausible that the northern route allowed direct access from Sakhalin to the Wakkanai area at the northern tip of Hokkaido, or that the journey could have been completed with only a short voyage. Even so, if that were the case, there should be cultural connections between the Sakhalin area and northern Hokkaido. Yet, traces of such connections are almost entirely absent.

The Jomon period has long been defined by archaeological artifacts such as pottery styles, yet from this perspective, Sakhalin and northern Hokkaido differ greatly in character, making it difficult to identify any continuous Jomon cultural linkage. Another possibility that has drawn attention is the island-hopping route via the Kuril Islands. This route involved traveling by boat from Siberia, hopping across multiple islands, and eventually reaching the Shiretoko or Nemuro regions of Hokkaido. Interestingly, cultural similarities to the Jomon have long been noted on this side.

However, since World War II, this region has been overshadowed by the Northern Territories dispute between Japan and Russia, with each side conducting its own surveys at different times. Due to diplomatic constraints, consistent, unified research has been impossible, and the mystery remains unresolved. It is therefore expected that it will take considerable time before the full picture of this route emerges, making the normalization of relations between the two countries an urgent task.

What further complicates the study of northern-route Jomon is the question of how to place the Ainu (アイヌ). The word “Ainu” is used sometimes for people and sometimes for culture, and I often feel the two are spoken of without being distinguished. The Ainu are generally regarded as Indigenous, but this applies only to part of Hokkaido and—crucially—“Ainu = Jomon” is not a simple equation. As pointed out in the excellent 1960s work 『アイヌの墓 考古学からみたアイヌ文化史』 (“Ainu Graves—A Cultural History of the Ainu from an Archaeological Perspective”), the word “Ainu” began to be used in the Meiji period as a category of people and was later used to describe a culture, and the two have overlapped without being distinguished. This is a fundamental problem, and Hokkaido’s history begins to come into view only when we carefully untangle how the word has been used.

It is known that large-scale contact between the Ainu and mainland Japan began around the Edo period, but tracing the history further back reveals other possibilities. As noted earlier, the term “Ainu” only became common after the Meiji Restoration, and prior to that it does not appear in Japanese sources. This is because “Ainu” is derived from their own language and was not a common term on the Japanese side. Consequently, the first appearance in literature is in the Nihon Shoki, compiled in 720, where the earliest reference is to “Emishi” (蝦夷) in the fifth year of Empress Saimei’s reign (around 659). In reading this account, pronunciation is essential. “蝦夷” was originally read as emishi, but for some reason, around the 12th century, the reading changed despite the characters remaining the same.

Around the 12th century, when this pronunciation shift occurred, something significant was happening in Hokkaido. At that time, the land inhabited by groups descended from the Jomon saw the arrival—along the northern Hokkaido coast from Sakhalin—of the Okhotsk people, a group from a completely different cultural sphere who had lived along the Okhotsk Sea coast on the continent. In Japan, this was the Kamakura period, when warrior rule was taking hold. Meanwhile, on Hokkaido’s largely unrecorded frontier, the arrival of these different groups drastically changed the fate of the descendants of the Hokkaido Jomon.

In other words, Ainu culture has a relatively recent layer in Japanese history, formed around the Kamakura period as Okhotsk migrants from the north and descendants of the Jomon came together. It overlaps with the Jomon but is not identical to it. Recent genetic research, which has advanced rapidly, confirms that Ainu people carry strong Jomon-derived elements, but that these are not the whole picture, and that they also carry distinctive genetic elements found among northern continental peoples—elements that the Jomon did not have. This leads to the inference that the pronunciation change of “蝦夷” in the 12th century may have been because forces such as the Minamoto based in Kamakura had detected these changes in Hokkaido. In fact, Yoshitsune Minamoto (1159–1189), a key figure in the rise of the Minamoto, is said in conventional history to have died in present-day Iwate after opposing his brother Yoritomo Minamoto, but my own long-standing investigations into him suggest that multiple legends indicate he may have fled as far as Hokkaido.

This was precisely the period when the arrival of the Okhotsk people was disrupting the lives of Hokkaido’s Jomon descendants. Indeed, Yoshitsune is praised as a kamuy (“kami” in Ainu) among the Ainu in south-central Hokkaido.

I have always regarded the Japanese language as a “language of sound,” and in studying ancient Japan I pay particular attention to changes in pronunciation. In this major research project as well, I intend to form a clear outlook on this point.

How, then, did the large-scale migrations of the Jomon—believed to have entered via the northern route—actually occur? Why is there no cultural connection between Jomon in Sakhalin and Hokkaido? And was this part of a broader eastward human migration, or a movement in an entirely different direction that we have yet to discover? To solve the many mysteries of Japanese history, investigations into both the northern and southern routes are indispensable.