The tumuli constructed from the beginning and the early phase of the Kofun period are considered an extension of the Yamato-style square tombs with moat surrounding and the Izumo-style tombs covered with a heap of earth, whose four corners are protruding outward, both of which were built in the Yayoi period.
古墳時代初頭ないし前期に築かれるものは、弥生時代の大和風の方形周溝墓や出雲風の四隅突出型墳丘墓の延長と考えられる。