著者

藤尾 慎一郎

出版者

国立歴史民俗博物館

雑誌

国立歴史民俗博物館研究報告 = Bulletin of the National Museum of Japanese History (ISSN:02867400)

巻号頁・発行日

vol.185, pp.155-182, 2014-02

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弥生文化は,鉄器が水田稲作の開始と同時に現れ,しかも青銅器に先んじて使われる世界で唯一の先史文化と考えられてきた。しかし弥生長期編年のもとでの鉄器は,水田稲作の開始から約600年遅れて現れ,青銅器とほぼ同時に使われるようになったと考えられる。本稿では,このような鉄の動向が弥生文化像に与える影響,すなわち鉄からみた弥生文化像=鉄史観の変化ついて考察した。従来,前期の鉄器は,木製容器の細部加工などの用途に限って使われていたために,弥生社会に本質的な影響を及ぼす存在とは考えられていなかったので,弥生文化当初の600年間,鉄器がなかったとはいっても実質的な違いはない。むしろ大きな影響が出るのは,鉄器の材料となる鉄素材の故地問題と,弥生人の鉄器製作に関してである。これまで弥生文化の鉄器は,水田稲作の開始と同時に燕系の鋳造鉄器(可鍛鋳鉄)と楚系の鍛造鉄器(錬鉄)という2系統の鉄器が併存していたと考えられ,かつ弥生人は前期後半から鋳鉄の脱炭処理や鍛鉄の鍛冶加工など,高度な技術を駆使して鉄器を作ったと考えてきた。しかし弥生長期編年のもとでは,まず前4世紀前葉に燕系の鋳造鉄器が出現し,前3世紀になって朝鮮半島系の鍛造鉄器が登場して両者は併存,さらに前漢の成立前には早くも中国東北系の鋳鉄脱炭鋼が出現するものの,次第に朝鮮半島系の錬鉄が主流になっていくことになる。また弥生人の鉄器製作は,可鍛鋳鉄を石器製作の要領で研いだり擦ったりして刃を着けた小鉄器を作ることから始まる。鍛鉄の鍛冶加工は前3世紀以降にようやく朝鮮半島系錬鉄を素材に始まり,鋳鉄の脱炭処理が始まるのは弥生後期以降となる。したがって鋳鉄・鍛鉄という2系統の鉄を対象に高度な技術を駆使して,早くから弥生独自の鉄器を作っていたというイメージから,鋳鉄の破片を対象に火を使わない石器製作技術を駆使した在来の技術で小鉄器を作り,やがて鍛鉄を対象に鍛冶を行うという弥生像への転換が必要であろう。Starting to use iron implements at the same time as the initiation of the wet rice cultivation, the Yayoi culture has been considered as the only prehistoric culture in the World that started using iron implements before bronze implements. According to the long chronology of the Yayoi culture, however, iron implements are considered to have appeared 600 years after the initiation of the wet rice cultivation, at the almost same time as the appearance of bronze implements. This article examines changes in the iron historical view of the Yayoi culture (the historical view of the iron culture) to reveal how the development of iron as assumed above affects the perspective of the Yayoi culture.Previous studies did not consider that iron implements in the early Yayoi had any substantial influences on the Yayoi society because of their limited use such as for delicate work on wood containers. Therefore, there are no significant differences when assuming that the first 600 years of the Yayoi period did not have iron implements.The new historical view, however, makes profound differences in the place of origin of iron materials and in the iron manufacturing techniques of Yayoi people. With regard to iron implements in the Yayoi culture, the conventional view suggested that there were two types of iron appearing at the same time as the initiation of rice cultivation: cast iron (malleable cast iron) originated from the Yan State and tempered iron (wrought iron) originated from the Chu State. Previously, Yayoi people were considered to have had advanced techniques to make iron implements, such as decarbonizing cast iron and forging tempered iron, in the latter half of the Early Yayoi period.According to the long chronology of the Yayoi culture, however, cast iron originated from the Yan State first appeared in the early forth century B.C., and then tempered iron originated from the Korean Peninsula followed in the third century B.C., resulting in the coexistence of both types of iron. Moreover, decarbonized-cast-iron steel originated from the Chinese northeast region appeared before the birth of the Former Han Dynasty. In the end, the wrought iron from the Korean Peninsula gradually went mainstream.In addition, the iron manufacturing technology of Yayoi people started with edging small iron implements by sharpening and grinding malleable cast iron in the same way as making stone tools. The forging of tempered iron started with Korean-origin wrought iron after the third century B.C., and the decarbonizing of cast iron commenced after the Late Yayoi period.In summary, it is necessary to change the perspective of the Yayoi iron culture. Yayoi people did not make their own iron implements from two types of iron, cast and tempered iron, by using their advanced technology at an early stage. Instead, they started with making small implements of cast iron pieces by using conventional fireless techniques to produce stone tools at first and then developed their techniques to forge tempered iron.