Later in this early 'Kofun' period, a circular tumulus appeared and was positioned as a precursor to the keyhole-shaped mound; then another 'Kofun' development was of a large square tumulus, and this appeared only in the distinctively cultural sphere of Izumo Province; also, this large square tumulus seemed to be developed from yosumi tosshutsugata funkyubo (square mounds whose four corners protruded outward).
その後、前方後円墳のさきがけと位置付けられる円墳、出雲文化圏特有の四隅突出型墳から変化した大型方墳が代表的である。