The iron sword does not have an era, but it seems to have been made in the middle of the fifth century from the shape of short metal body armor with rivets and iron arrowhead collected in the wooden coffin.
鉄剣に紀年が書かれていないが、木棺に収められていた鋲留短甲と鉄鏃の形式から五世紀中葉と見られている。