First, it has been one of the assumptions that during this time period, particularly in the mid-seventh century to the mid-eighth century, the population in this region north of Taga was Emishi in nature or under the control of these people. That may not be the case.
Second, there is a definite difference found among the burial sites as to the types of skeletal remains found. This needs to be further studied to find out why this is the case, but burial tomb number 64 has a number of Jomon related people interred in it. In other burial sites the population interred are more related to contemporary Japanese of that time: that is, the skeletal remains closely resemble Yayoi remains found in northern Kyushu and those from the Kanto kofun. There is a definite contrast found between them and the Jomon type of skeletal remains that have more in common with the Ainu, Epi-Jomon and Jomon remains. Generally, the latter skulls tend to be more square or angular and the facial features more pronounced (higher or more pronounced nose bridges, deeper eye sockets) along with smaller front teeth, and when compared to other Jomon sites, they tend to be taller. This pattern is repeated here, however, with a difference where the tooth pattern is more in line with contemporary Yayoi samples.
The question that begs to be answered is why is burial tunnel 64 different from other burial sites even though they are all in the same area and from the same time period? Does this relate to some of the retainers employed by the builder of these tombs?
One of the reasons why the first assumption mentioned above may not be correct is that some of the pots that were recovered from the burial sites are signed by a known potter (dai-sha-jin) whose family was employed by the Fujiwara. If this is a case where one of the potters moved into the area which is likely then how can we account for the fact this area was under Emishi control? This particular signature is known from other sites and come from this particular family employed by the Japanese. Do these simply represent trade goods?
Other burial site remains indicate that they are very similar and in some cases identical to burial sites found in the Kanto (in Chiba prefecture). Were these burial sites made by immigrants or the descendants of immigrants who originated from that area? The known skeletal types from the burial sites reinforces this initial finding, except for burial tunnel 64. The initial conclusion of the study is that the site was originally under the control of a gozoku (or great family) who used this burial site. And that this family was originally from the Kanto, perhaps originally from the Chiba area. They represent Japanese immigrants who settled this area and may have had connections with the central Yamato authorities. They may have been connected with a known family, the Michishima, who was part of the fushu (Emishi who were Japanese allies) who were not of native origin, but had lived in the area long enough as to be considered locals. Was this burial site the Michishima clan site? If it was it would go a long way to explain part of the mystery of the fushu as being composed not just of Emishi people, but of local Japanese living in the Tohoku as well, confirming Nagaoka’s line of argument. The real revision would have to be that this area was under the control of a Japanese clan instead of a native clan.
Historians know that the Michishima family was a local fushu that lived in the area because the clan played a central role in the fighting that followed Azamaro's defection to the Emishi side. Again, this is still speculation as there is no definite proof that this burial site was under the Michishima. Whether this site was connected to the Michishima or not, what is clear is that Japanese settlement preceded the Japanese conquest and control of the area by a few centuries.
Still, it is too early to draw set conclusions because the study is still in its initial stage. However, why burial tunnel 64 contains the remains of Jomon type people is a mystery. If the initial study holds up that this site was the burial site of a local Japanese family then certainly burial 64 must represent natives who were employed by them perhaps as retainers. This finding also lays to rest the notion that the natives were not related to the later Ainu. This is evidence that Ainoid type peoples lived in the Tohoku region well into the historical period, and not just through the Jomon peoples of the distant past (before the Yayoi incursions of the Kofun period) as some have argued. The definitive study is still being done on the skeletal remains from many burial sites, including this one, that have been found in areas that have traditionally been seen as under Emishi control.