[Article] The Transformation of Eighth-Ninth Century Settlements in Fukuoka City (Abstract)

application/pdf畿内，東国，北部九州の古代集落は，8世紀の安定期を終えた後に，それぞれ異なった展開をたどる。すなわち，畿内では9世紀に入ると不安定化し，東国では10世紀に入って衰退するのに対し，北部九州では9世紀初頭に衰退してしまうのである。しかし，衰退したり不安定化したりする原因については，あまりはっきりとしていない。集落の衰退・消滅の背景を探るには，まずは個々の遺跡の景観を復原していくことから始めるしかあるまい。 本稿では，福岡市教育委員会が刊行した発掘調査報告書の悉皆調査を踏まえて，福岡平野の中心部を貫流する御笠川左岸の低位段丘上に，8世紀初頭から末まで稠密な集落群が営まれたことを確認した上で，その住人たちの食料生産の基盤であった可能性がある御笠川左岸の低湿地・微高地，及び右岸の低湿地・微高地上の水田や集落の展開を追ってみた。その結果，8世紀末から9世紀初頭にかけて起こった大洪水によって水田面が広範に埋没したことが周辺住民の生産基盤を破壊し，これが原因となって集落が途絶えたのではないかと考えた。 御笠川右岸には延暦年間に設定された観世音寺の荘園があったが，同じ場所が勅旨田とされてしまったのは，そこが洪水によって埋没してしまい，荒廃してしまったためであろう。この水田面は厚い洪水砂によって一旦埋められ，再開発は容易ではなかった。現地は貞観年間でも，ところどころに新開田や再開発田が点在する景観だったことが文献史料から窺えるのである。 このように，福岡市の中心部分にあった古代集落に関しては，その衰退の大きな原因が水害という自然災害にあったことを，発掘調査の結果と文献史料とを総合して明らかにすることができ，その復旧が容易ではない状況も，関連史料によって説明することができた。Ancient settlement in Kinai, the Togoku,and northern Kyushu followed different paths of development following a period of stability in the eighth century. In contrast to the Kinai area, where settlements became unstable in the ninth century, and the Togoku, where they declined in the tenth, those in northern Kyushu declined in the early ninth century. However, the cause of this decline and instability is not clear. The only way to find out the background of the decline and disappearance of the settlements is to restore the landscape of each archaeological site. This paper is based on an exhaustive survey of excavation reports published by the Fukuoka City Board of Education. I was able to confirm that during the eighth century a dense group of settlements was built on the low terraces on the left bank of the Mikasa River, which runs through the center of the Fukuoka Plain. Next, I traced the development of paddy fields and settlements on the low wetlands and slightly elevated areas of both the left and right banks of the Mikasa River. I found that extensive burial of paddy fields as a result of the great floods that occurred from the end of the eighth century to the beginning of the ninth destroyed the production base of local residents, causing the settlements to disappear. On the right bank of the Mikasa River existed an estate that was founded in the Enryaku year-period (782-806) and originally belonged to Kanzeonji Temple. The estate was later converted to an imperial landholding (chokushiden), probably because it was buried by the floods and turned into wasteland. Paddy fields here were buried in thick sand by the floods, and redevelopment was not easy. It can be seen in written records that even during the Jōgan year-period (859-877), this area’s landscape was dotted with newly developed paddy fields and redeveloped fields. In this way, It can be shown through a combination of archaeological excavations and historical documents that the major reason for the decline of ancient settlements in the central part of Fukuoka City was flood damage; the difficulty people faced in restoring the settlements can also be seen in relevant historical documents.departmental bulletin pape