송서
Archaeological records and ancient Chinese sources Book of Song indicate that the various tribes and chiefdom of the Japanese Archipelago did not begin to coalesce into more centralized and hierarchical polities until 300 (well into the Kofun period), when large tombs begin to appear while there were no contacts between the Wa and China. Some describe the "mysterious century" as a time of internecine warfare as various local monarchies competed for hegemony on Kyūshū and Honshū.