The Abe clan (Oshu) (安倍氏 (奥州))
The Abe clan was a Gozoku (local ruling family) in Mutsu Province (later Rikuchu Province, and Oshu is another name of Mutsu Province) who lived during the Heian period.
The roots of the Abe clan have not been clarified, but according to the family tradition that the Abe clan passed down in the "Hiraizumi Zakki" (Miscellaneous notes on Hiraizumi), their earliest ancestor was Abihiko, the older brother of Nagasunehiko, the king of the Kinai region (provinces surrounding Kyoto and Nara) who had been killed by Emperor Jinmu, and the Abe clan originated when Abihiko fled to Tsugaru. Similar descriptions can be found in the Ando and the Fujisaki genealogy; therefore, apart from ascertaining facts, it is for certain that the descendants of the Abe clan identified themselves in such a way.
Studies in the later years have also presented with opinions that the origin of the Abe clan could be sought through ABE no Hirafu (the Fujisaki genealogy) who forced the Ezo (natives in the northern districts of Japan) in Akita into submission; or by changing the reading of the name from "abe" to "ape" from the standpoint of identifying the Ezo with the ancestors of the Ainu tribe, the Abe clan could be seen as completely indigenous. In turn, it is also said that any one of the Abe clan who was a central government official, came down to Oshu and left his offspring at the place of his post, or that the Ezo (Fushu [barbarians]) who had submitted themselves to the Imperial Court were the ancestors of the Abe clan.
Discussion on "Chief of Fushu"
While the opinion that the Abe clan was the Chief of Fushu (chief of barbarians, that is, the influential persons who had been selected from Fushu by the authority of the Yamato Imperial Court) is widely disseminating, there are no descriptions in documents stating the Abe clan to be the Chief of Fushu, with the exception of a description, "the late Chief of Fushu ABE no Yoritoki," in Dajokanpu (official documents issued by Dajokan, Grand Council of State) in 1064.
The Abe Clan as Military Aristocracy
It has hitherto been the mainstream to recognize the Abe clan as a local Dogo (powerful family) in the Tohoku region, and to interpret Zen Kunen no Eki (the Earlier Nine Years' War) as a rebellion against the domination over the remote regions by the central government. However, in accordance with the progress of the studies in recent years on the military aristocracy, a view to regard the Abe clan as "Tsuwamono" (soldiers) characteristic of the Imperial Court State have emerged. "Tsuwamono" were military force not specified in the ritsuryo system (a system of centralized government based on the ritsuryo code), and they were a kind of mercenary troops that were utilized to suppress civil disorder incidents which frequently occurred in the provinces. Unlike the samurai (warriors) of the Medieval (Kamakura and Muromachi) period, they are thought to have been groups of soldiers who were not particularly concerned about possessing and ruling of land.
Yukihiko SEKI has indicated that, apart from the military aristocracy who were descendants of the central nobles such as the Taira clan, the Minamoto clan, and the Fujiwara clan of the Hidesato line, there may also have been those who had changed into the military aristocracy from the local Dogo under the authority of the central government, and argued that the Abe clan may also have been one of this kind. As its corroborating evidence, Seki indicated that ABE no Yoritoki is called "Daibu" (a common name of those who had been granted Goi [Fifth Rank] as an official rank) in "Mutsu Waki" (A Record of Mutsu, or A Chronicle of the Earlier Nine Years' War).
Zen Kunen no Eki and the Fall the Abe Clan
The Abe clan extended their power through marriages and so on, and they were most influential in the time of ABE no Yoritoki who was a child of Tadayoshi. The Abe clan established its foothold in Okuroku-gun (inland six districts, at present the inland area of Iwate Prefecture) surrounding the Kitakami-gawa River, and exhibited great influence on the vast regions from Nukanobu (at present the eastern part of Aomori Prefecture) to Watari and Igu (at present the southern part of Miyagi Prefecture). Later on however, ABE no Sadato came into conflict with the Imperial Court, and the Abe clan fought a series of battles called "Zen Kunen no Eki" against the suppression forces headed by MINAMOTO no Yoriyoshi. The Abe clan continued to predominate over Yoriyoshi throughout all battles, but after the Kiyohara clan, the master of Fushu in Senboku of Akita, participated in the war after accepting Yoriyoshi's repeated requests, Sadato was unable to continue fighting, and was defeated. The Abe clan lost its power.
ABE no Muneto who was the third son of Yoritoki, and ABE no Masato who was the fifth son of Yoritoki, were exiled to Iyo Province (later to Munakata, Chikuzen Province) and Higo Province, respectively. Moreover, Yoritoki's daughter who had been the wife of FUJIWARA no Tsunekiyo, a local ruling family in Watari (Watari-cho, Miyagi Prefecture), became the wife of KIYOHARA no Takesada, and her son (later FUJIWARA no Kiyohira) was also taken in and was adopted by Takesada. The Kiyohara clan succeeded to the position of the Abe clan, but Go Sannen no Eki (the Later Three Years' War) led to their downfall, and FUJIWARA no Kiyohira succeeded the Kiyohara clan, establishing the golden age of the Oshu Fujiwara clan.
The Abe clan fell at one time due to Zen Kunen no Eki, but those who claimed themselves as the descendants of the Abe clan have appeared, prospered, and lived to this day.
Particularly famous among them are the Tsugaru Ando (安東 or 安藤) clan who claimed themselves as the descendants of ABE no Sadato, the Akita clan who were descendants of the Tsugaru Ando clan that were active as a Sengoku daimyo (Japanese territorial lord in the Sengoku period), the Kyushu Matsuura Party who claimed themselves as the descendants of ABE no Muneto, and Shinzo ABE who is a descendant of the Kyushu Matsuura Party and was a Prime Minister in the Heisei era.
Also, Mitsumasa YONAI who was active as a Prime Minister and a Navy Minister in the early Showa era took pride in being the descendant of ABE no Sadato.