The Abe clan and their origins is disputed. Part of the reason for this is a study of their descendant's mummies, the Northern Fujiwara, established that they were like other contemporary Japanese. Since then their ancestral connections have also come under question. Before this it was assumed that the Northern Fujiwara and their lineage along with the Abe were descendants of the Emishi people, the aboriginal inhabitants of the Tohoku who had fought against Yamato authority in centuries past. After the finding it was clear that they were not. Now, the state of the Abe is not conclusive since it can be argued either way, since the rulers of the Fujiwara preserved as mummies were a century ahead of the Abe, and could reflect intermarriage with contemporary Japanese. However, the Abe can be traced back into the ninth century having lived much longer in the Tohoku, but here it gets very confusing. Out of the confusion, most likely the Abe were either an ancient Japanese family who moved into the area before the Yamato wars with the Emishi (the eighth century), or they were of ninth century Japanese origin. If they had moved pre-conquest then it can be argued that they most likely had ties with the local Emishi, and calling them "natives" would not be a stretch. However, if they moved post-conquest then they cannot claim to be local Emishi.Whatever the case, their clan is of interest not only in determining if they were local Emishi, but even if they were not they shed light on Japanese who sided with the Emishi. Examining the Abe sheds light not just on the Abe clan, but how much the Tohoku region changed after the conquest. Before the conquest the area was clearly Emishi or non-Japanese Jomon in the majority. After the conquest it could be said that the Japanese families and clans began to form the majority in the region in the very heartland of the Emishi resistance, the country called Hitakami by the Japanese court.The Abe name can be traced into the ninth century. All people who held this name were Japanese who were employed by the state. There were two mentioned who held the office of chinjufu-shogun, Abe Koretaka dated 878 and Abe Mitora in 884. There are two instances mentioned of Mutsu governor, an Abe Kiyoyuki in 886, and another, Abe Tsunemi in 940. If these were Abe relations connected to the eleventh century clan then they were a very influential family in the region from at least the ninth century, and the positions they held betray their ethnicity as these were positions that could only be held by well connected Japanese. For example, farmers or craftsmen could not hold these positions, however, the highest ranking soldiers or members of the nobility could.There is a possibility, though unlikely, that they were an ancient family that were related to the imperial lineage. The Abi clan, said to have been related to Nagasue-no-hiko, a semi-legendary Yamato prince, is said to have fled the Yamato region (central Japan) to the northern Tohoku region after losing a battle against the prince in the Nihon-shoki. The Abi name is said to have become Abe. If true they would have moved into the Tohoku centuries before the Yamato wars there, and thus would have to be seen as a frontier Japanese clan who sided with the Emishi against Yamato, and who had adopted their culture. They would have had to in order to live there for so long. However, this scenario is impossible to corroborate.There is also the possibility that they originated near the river Atsubi in Iwate, and that this name "Atsubi" was their original family name, and that eventually this changed to Abe. This is cited as possible evidence for the Abe as aboriginal Emishi. However, this is also not verifiable--there is no Atsubi clan mentioned and nothing indicates that they were originally from the Atsubi area.This leaves only the strong possibility that the office holders named Abe from this region dated from the ninth century are the Abe of later Japanese history. Stronger still when their later history as the most powerful family in the Mutsu region is considered.
Reference:Takahashi, Takashi. Emishi no matsuei. Tokyo: Chuo-shinsho: 1991.Kenjiro 2007.12.18