水稲農耕開始後，長時間に及んだ金属器不在の間にも，武器形石器と転用小型青銅利器という前段を経て，中期初頭に武器形青銅器が登場する。一方，前段のないまま，中期前葉に北部九州で小銅鐸が，近畿で銅鐸が登場する。近畿を中心とした地域は自らの意図で，武器形青銅器とは異なる銅鐸を選択したのである。銅鐸が音響器故に儀礼的性格を具備し祭器として一貫していくのに対し，武器形青銅器は武器の実用性と武威の威儀性の二相が混交する。しかし，北部九州周縁から外部で各種の模倣品が展開し，青銅器自体も銅剣に関部双孔が付加されるなど祭器化が進行し，北部九州でも実用性に基づく佩用が個人の威儀発揚に機能し，祭器化が受容される前提となる。各地域社会が入手した青銅器の種類と数量に基づく選択により，模倣品が多様に展開するなど，祭器化が地域毎に進行した。その到達点として中期末葉には，多様な青銅器を保有する北部九州では役割分担とも言える青銅器の分節化を図り，中広形銅矛を中心とした青銅器体系を作り上げる。対して中四国地方以東の各地は，特定の器種に特化を図り，まさに地域型と言える青銅器を成立させた。ただし，本来の機能喪失，見た目の大型化という点で武器形青銅器と銅鐸が同じ変化を辿りながら，武器形青銅器は金属光沢を放つ武威の強調，銅鐸は音響効果や金属光沢よりも文様造形性の重視と，青銅という素材に求めた祭器の性格は異なっていた。その相違を後期に継承しつつ，一方で青銅器祭祀を停止する地域が広がり，祭器素材に特化していた青銅が小型青銅器へと解放されていく。そして，新たな古墳祭祀に交替していく中で弥生青銅祭器の終焉を迎えるが，金属光沢と文様造形性が統合され，かつ中国王朝の威信をも帯びた銅鏡が，古墳祭祀に新たな「祭器」として継承されていくのである。

After starting rice cultivation, people used weapon-shaped stone tools and diverted small sharpedged bronze implements to different purposes for a long time, while there were no metal implements. Following this preliminary stage, weapon-shaped bronze implements appeared in the beginning of the Middle Yayoi period. On the other hand, skipping the preliminary stage, small bronze bells appeared in northern Kyushu and bronze bells in Kinki in the first half of the Middle Yayoi period. In other words, the area around Kinki consciously adopted bronze bells rather than weapon-shaped bronze implements. Having a ceremonial nature as a sounder, the bronze bells came to be used for nothing but ritual purposes. In contrast, the weapon-shaped bronze implements came to mix two purposes: practical utility as a weapon and dignity demonstration as a military power. While various kinds of imitations were appearing in the periphery and outside of northern Kyushu, however, the bronze implements as a whole also came to be used in rituals, such as bronze swords with two holes in the joint part. In northern Kyushu as well, people started to wear swords not only for practical purposes but also for demonstration of personal dignity, which led to the acceptance of bronze swords as ritual implements. Respective areas promoted the development of bronze tools into ritual implements in their own ways while a wide variety of imitations appeared depending on the choice of type and amount of bronze implements each local society acquired. Eventually, in the end of the Middle Yayoi period, a variety of bronze tools fell into different categories with different roles in northern Kyushu, which established a bronze system centering on medium broad bronze spearheads. On the other hand, focusing on particular types of bronze implements, each area in Chugoku/Shikoku region and eastward developed its own local bronze tools. Although both weapon-shaped bronze implements and bronze bells lost their original purposes and became larger in size, they accented different features of the material; whereas weapon-shaped bronze implements got to emphasize the function of dignity demonstration with metallic luster, bronze bells attached importance to the creation of patterns rather than acoustics and metallic luster. While this difference was inherited later, more and more areas stopped using bronze ritual implements, and bronze came to be used not only for ritual implements but also for other small tools. Then, the Yayoi bronze ritual implements disappeared, newly replaced by the Kofun ritual implements. Carrying the prestige of Chinese dynasties, bronze mirrors were adopted as the Kofun ritual implements while inheriting both of the accented features of the Yayoi ritual implements, metallic luster and pattern creation.

source:https://www.rekihaku.ac.jp/outline/publication/ronbun/ronbun8/index.html#no185