Large keyhole-shaped tomb mounds of an early date apparently constructed using the techniques of groups in Kibi and Asan (East Shikoku) were distributed centering in Yamato, and spread throughout Japan in subsequent years.
吉備、阿讃（東四国）の勢力の技術によると見られる初期の前方後円墳が大和を中心に分布しており、時代が下るにつれて全国に広がっていること。