The Genealogy of Toyokiirihiko and the Kamitsukenu Region : On their Historical Characteristics

application/pdf『日本書紀』の崇神紀や景行紀などには，上毛野氏に係わる祖先伝承が掲載されている。この現象は東国出身氏旅としては異例であるが，内容は①始祖は崇神天皇の皇子の豊城入彦命，②東国の統治と蝦夷征討に関わる，③中央政権の構成氏族として外交・外征に参加している，といった点に要約される。 このような祖先系譜が採録された事情を知る上で，『紀』が撰修された時期の中央政権での上毛野氏の動向に注目する。それはこの時期の重要政策である出羽方面の律令的編成事業において，その出自の地である上野国の性格と密接に関わるものと考える。そこでは上野国は「随近国」と位置付けられて，関東平野の諸国に先んじて，征討や柵戸移民に目ざましい動きを示している。このことは上野国が関東平野の北西隅にあって，日本海側との往来の便地であると同時に，碓氷峠を掌握する要衝を占めるという地理的な要因にもとづくものとみなされる。 こうした様相から，中央政権が陸奥方面の統治を目指した時期には，陸路での要衝にあたる上毛野地域と下毛野地域の政治的安定と，人的・物的資源の供給を担う在地氏族の確保が不可欠な要件であったと推察される。『紀』で上毛野氏と下毛野氏が，東国統治を担った皇子豊城入彦命を始祖とし，その三世孫で蝦夷征討を行った御諸別王の子孫で東国に居付いたものであるとの系譜構造は，こうした地理的特性を反映したものとみてよい。 その実態は，史料では７世紀代のいくつかの記事から推察されるのみであるが，考古学的には総社古墳群を指標とした時，中央政権を背景とした上毛野地域の一元的統括が顕在化するのは７世紀前半からとみなされる。そうした政治的特性は，蝦夷地経営が大規模化し，それに応じた新たな「随近」地域である「坂東」が設定された８世紀中期に役割を終える。そのことは外部氏族による豊城人彦命系譜への参入といった現象をもたらしている。In the Sujinki and Keikoki of the “Nihon-Shoki” (Chronicle of Japan), the ancestral legend of the clan of Kamitsukenu is described. Such a phenomenon is exceptional for a clan which came from the Togoku (eastern Japan). The contents can be summarized as follows: (1) Their origin goes back to Toyokiirihiko, a prince of the Emperor Sujin. (2) The prince was engaged in the rule of the Togoku and subjugation of the Emishi race. (3) The clan of Kamitsukenu participated in diplomacy and foreign expedition, as a clan forming part of the central government. As background to the inclusion of such an ancestral geneaology, it can be mentioned that many talented members of the Kamitsukenu clan were appointed as middle-class government officials of the central government of the time, when the “Nihon-Shoki” was edited. These appointments to positions of trust are considered to be closely related with trends in Kozuke Province, their home area, in the important policies of that time; that is, the statutory organization of the Dewa Region. Here, Kozuke province was regarded as an obeydiant and close country, showing remarkable activity in subjugation and the migration of inhabitants (“Sakuko”), ahead of other provinces in the Kanto Plain. It can be conceived that the political characteristics of the Kozuke Province were created by its geographical factors as follows; it is located in the northwestern corner of the Kanto Plain, a convenient location for traffic with the Japan Sea side, and at an important position in the Usui Pass. Such an aspect must have been even clearer when the central government aimed to rule the Mutsu region, a little earlier. For this purpose, it is not difficuit to imagine that the control of the Kamitsukenu area, a strategic point for land traffic, and of local clans in charge of political stability and the supply of human and material resources, in the adjacent Shimotsukenu Area, was an essential requirement. In the “Nihon-Shoki”, it is described that Prince Toyokiirihiko, who ruled the Togoku, was the founder of the Kamitsukenu clan and the Shimotsukenu Clan, and that the descendants of his grandson, Mimorowake-o, who subjugated the Emishi, settled down in the Togoku. This structure of the genealogy can be considered to reflect the above geographic characteristics. The existence of these characteristics as fact remains only in several records of the 7th century, as far as historical documents go. However, from the archaeological viewpoint, using the Soja Tumuli Groups as an index, it can be considered that the unitary rule of the Kamitsukenu area backed by the central government became notable in the first half of the 7th century. The role of the special political features came to an end in the mid-8th century, when the management of the Ezo Area was upscaled, and “Bando”, or a new “subordinate and close” area, was established accordingly. This is also shown in the decline of the power of the Kamitsukenu clan within the central government, and the penetration of other clans into the line of Toyokiirihiko, as it were in inverse proportion to the decline.departmental bulletin pape