12/3 - 12/4/2014
Emergence of Standardized Tumuli (kofun) in the
Third-century Northern Kantô in Eastern Japan 弥生・古墳時代移行期の群馬県域における古墳出現過程
DOI Shohei土井翔平, Ph.D. Candidate in Archaeology, Meiji University
This paper explores the process behind the appearance of the highly standardized tumuli or kofun in the third-century northern Kantô region of eastern Japan. It has previously been a well-accepted hypothesis that keyhole-shaped tumuli appeared in eastern Japan in the middle third century under the cultural influence of the Tôkai region, Pacific coastal region of the central Honshu, and that people’s life style and mortuary practices came to be unified in the fifth century. The problem of this hypothesis is that it supposes that all the cultural influences from the west were uniform across the entire eastern Japan, which was not necessarily the case. In terms of methodology, it is also problematic that data are skewed toward large keyhole-shaped tumuli. The latter problem is particularly apparent in Gumma Prefecture, northern Kantô. While the overwhelming majority of tumuli of the mid-third century are small ones, from ten to 30 meters in length, discussion of the appearance of tumuli is based on keyhole-shaped tumuli of more than 100 meters in length.
In order to cope with these problems, the author has looked at all the tumuli of the mid-third century in Gumma Prefecture, paying particular attention to the mound form, mound size, pottery offered to the dead, and goods deposited with the dead. As a result of the author’s analyses, it has become clear that in the late third and early fourth centuries, there were two distinctive cultural flows from the Tôkai region. These two were spatially distributed on the northern side and southern side of the Tone River. As to mortuary rituals, the author has found that pots offered at tumuli morphologically changed from ritualistic ones in the fourth century to more practical ones in the fifth century. By paying attention to regionally and locally various patterns and taking several types of material cultures into consideration, the author’s research broadens our understanding of a very complex process that underlay the appearance of standardized tumuli in eastern Japan.
従来、古墳時代の東日本は東海地方からの影響の中で古墳文化が流入し、その中で大形の古墳が出現し、古墳時代中期段階に近畿地方から関東地方にかけて生活様式・墓制等々が統一されるという見方が一般的であった。しかし、この視点は、関東地方という広域に広がる西日本からの影響をすべて等質にとらえてしまうことと、大形の前方後円墳を中心に議論が構成される傾向があった。本稿の検討対象地域とする群馬県域においても古墳時代前期の東海地方からの古墳文化の影響が想定されているが、県内の墳墓としては墳長10～30ｍの小形の墳墓が検出数としては圧倒的に上回るにもかかわらず、その検討に挙がるのは墳長100ｍ以上の大形古墳が中心である。
そのため本稿では、県内で確認されるすべての墳墓を対象とし、墳形・規模・供献土器・副葬品に関して分析を行った。その結果、古墳前期において東海地方からの文化流入に2つの流れが想定され、それが利根川を挟み分布を異にして発展することが確認された。また、墳墓祭祀に関して、古墳時代前期から中期へ移行するに従い供献土器における壺が儀礼的なものからより実用的なものに変化していくことが、形態的分析から確認できた。
本研究において、これまで西日本からの一方面的な分析視点に対し、在地における多方面の資料の分析の結果によって古墳出現過程のより詳細な様相を捉えることができた。