<論説>前・中期古墳副葬鏃の変遷とその意義

Abstract

鏃は古墳時代全期間を通じて、多くの古墳からの出土がみられる器物であり、その変遷観の確立は、ひろく古墳の年代決定に資するものである。またそのような、どの時代の古墳からも出土するという鏃の資料的特性は、同一の器物に基づき古墳時代を通観して分析することを可能とする。しかしながら、そのような役割が期待されてきたにもかかわらず、古墳時代前期の鉄鏃・銅鏃は十分な編年的検討がおこなわれてこなかった。そこで本稿では、古墳時代前期および中期の鉄鏃・銅鏃の編年をおこなった。個々の鏃の形態変化の方向を示した後に、鏃の形態・組成の変化と共伴遺物の変遷が相関することを示した。そして、組成の変遷の画期をとらえることで四期、細別七段階の段階設定をおこなった。さらに、各期において流通している鏃形式と実際の古墳にみられる鏃組成との比較をおこなうことにより、前期中葉以降、鏃形式の刷新と並行して鏃の生産体制と流通機構が段階的に集約されていくあり様を明らかにした。

Iron and bronze arrowheads were buried in tombs throughout the Kofun period and it has been thought that they may provide an indication of the date of tumuli. In order to determine precisely when the tumuli were build, it is necessary to elucidate the transformation of arrowheads and clarify when a particular arrowhead shape was made. However, chronological studies, particularly of the early Kofun period, are inadequate. In this paper, I have aimed to establish the chronology of iron and bronze arrowheads in the early and middle Kofun period (from the middle third century to the late fifth century). First, I classified the arrowheads into 54 types based on the way an arrowhead is attached to an arrow and their shapes. Second, I divided 10 types into several subtypes that indicate different times of production. Third, I proved that the difference in subtypes really indicates a difference in the time of the production since the changes in subtype coincide with those in other funerary objects. I referred to many objects, such as Bronze mirrors with triangular rim and design of deities and animals, Japanese copies of them, Japanese Bronze mirrors, hoe-shaped bracelets, Cylindrical bronze objects and iron cuirass and so on. Fourth, I showed that in 28 tumuli that had a wide variety of assemblages of arrowheads and the other objects there is a correlation between the transformations of several varieties of the 10 types and the changes of the types and assemblages of the other objects. Through these examinations, I proved the rise and decline of all forms of arrowheads, establishing four stages of arrowheads through the early and middle Kofun period (phase I to IV). Then, I considered the systems of manufacture and distribution through a comparison of the entire assemblage and individual assemblages. For the purpose of this study, the entire assemblage means all types of arrowheads that existed at any one stage and an individual assemblage means the complex of arrowheads buried in any one tumulus. At phase I and II the entire assemblage consists of many shapes and individual assemblages from each tumulus differ greatly. At phase III the number of the shapes included in the entire assemblage decreases and the individual assemblages become uniform. The entire and individual assemblages begin to resemble one another. At phase IV the tendency grows more pronounced. The number of shapes included in the entire assemblage diminishes more, and individual assemblages are standardized. The entire and individual assemblages closely resemble one another. In short, in spite of the introduction of new arrowhead shapes at each stage, the number of shapes gradually diminishes. The changes in shapes and assemblages occurred at the time approaching the uniformity of phase IV. Consequently, arrowhead style had been standardized since the early fourth century (phase II). For this reason I think that until the beginning of the fourth century (phase I) the manufacturing system varied and distribution system was limited. Then, the manufacturing system had been united and the distribution system spread its boundaries step by step from the early fourth century (phase II). The unity of manufacturing system and the widening of the distribution system, which started in the early fourth century, occurred simultaneously with introduction of early types of iron cuirass (tatehagiita kawatoji tanko and houkeiban kawatoji tanko), which are thought to have been distributed by the central polity of ancient Japan. New forms of arrowheads that were adopted early in the fourth century and late fourth century (phase II・III) were frequently associated with these iron cuirass. Consequently I surmise that the innovation of shapes and assemblages and the expansion of the manufacturing and distribute systems of arrowheads were promoted by the central polity of ancient Japan.