[論文] 古代北方交流史における秋田城の機能と意義の再検討

最近，知床半島における神功開宝の出土，根室半島での秋田産須恵器の出土などの新たな知見により，8～9世紀の本州・国家と北海道との交流の様相が改めて脚光を浴び，そのなかで出羽国・秋田城の果たした役割も問いなおされている。7世紀後半に発端する倭・日本の日本海ルート重視の北方政策は，北海道と本州北部との交流の変遷にも影響を及ぼした。8世紀には，続縄文文化期以来の在地的な交流を基盤とする太平洋側ルートが存続したが，秋田城における朝貢・饗給の定例化に伴い，9世紀初頭までに日本海ルートが卓越し，北海道と本州北部との交流は秋田城交易に収斂される。秋田城の構造や，横走沈線文土器，須恵器の出土状況などもこうした想定を裏付ける。その一方で，9世紀の秋田城交易は，王臣家・国司や富豪層らの独自の経済活動を内在し，より多様化する兆候をみせていた。9世紀初頭の改修に伴う秋田城の構造変化は，同時期における朝貢・饗給の質的変化と連動していた可能性がある。秋田城が北方世界の「交易港」として機能した8世紀中葉～9世紀の期間，これに寄生・便乗しつつ生まれた経済的・社会的な諸関係は，秋田城交易の内実を変質させ，9世紀末～10世紀に進展する次代の北方交易体制を準備した。9世紀の秋田城交易には，同時代に東アジア海域の国際交易に乗り出していた新羅・唐の海商が関心を寄せていた形跡もある。承和期に北部九州で新羅人張保皐との国際交易をおこなった文室宮田麻呂は，奥羽社会に深い関係をもつ文室大原や綿麻呂らと近親であり，近江を拠点に北方世界との交易に関与していた蓋然性がある。文室氏のような王臣家の活動を介して，古代の秋田城とその周辺は，北方世界と東アジア海域の国際交易をつなぐ接点としての側面をみせることがあったのである。

Recent findings, such as the excavation on the Shiretoko Peninsula of a Jingu-Kaiho coin and the discovery on the Nemuro Peninsula of sueki earthenware that had been produced in Akita, are once again spotlighting exchanges between Hokkaido and the ancient state of Japan on Honshu, the main island of Japan, in the eighth and ninth centuries. In this context, the roles played in such exchanges by Akita Castle in Dewa Province are also being reassessed.Japan’s late seventh century northern policy, which placed importance on the Sea of Japan route, affected exchanges between Hokkaido and northern Honshu. While a Pacific route, based on local exchanges dating from the Epi-Jomon culture period, also existed in the eighth century, the Sea of Japan route had presumably gained prominence by the early ninth century, with exchanges between Hokkaido and northern Honshu dominated by trade through Akita Castle, as Emishi people had periodically paid tribute to the provincial government at the castle, which had reciprocated by holding feasts for them. The structure of Akita Castle and the excavation of pots with transverse grooved-line patterns and sueki earthenware support this assumption.Meanwhile, trade through Akita Castle in the ninth century showed signs of diversification, as it included independent economic activities by imperial family members, aristocrats, provincial governors, and wealthy people. The renovations and structural changes to the castle in the early ninth century may have been connected with qualitative changes that occurred in tributes and feasts during the same period. Akita Castle served as a “port of trade” in the north from the mid-eighth to ninth centuries, and various socioeconomic relations that parasitized or piggybacked on that status changed the nature of trade through Akita Castle, paving the way for a next-generation northern trade system that thrived from the end of the ninth century into the 10th century.Some evidence shows that trade through Akita Castle in the ninth century gained the attention of maritime merchants in Silla and Tang who embarked on international trade during the same period across East Asian seas. Funya no Miyatamaro, who traded in northern Kyushu during the Jowa era (834 to 848) with Jang Bogo, a powerful maritime figure from Silla, was a close relative of Funya no Ohara and Funya no Watamaro, who had deep ties with the Ou (Tohoku) society, and it is therefore plausible that Funya no Miyatamaro, based in Omi Province, was involved in trade with the north. Activities by the Funya clan and other imperial family members and aristocrats offer a glimpse of Akita Castle and its surroundings in ancient times as a point of contact for international trade in the north and across East Asian seas.

source:https://www.rekihaku.ac.jp/outline/publication/ronbun/ronbun10/index.html#no232