Larger keyhole-shaped tumuli with a burial mound longer than 100 meters were concentrated in the Nara Basin and the Kinai region (five central provinces surrounding the ancient capitals of Nara and Kyoto, namely Yamato, Kawachi, Settsu, Izumi, and Yamashiro that are now the municipalities of Kyoto and Osaka and the prefectures of Nara and Hyogo) including Furuichi-kofun Tumuli Group, with some exceptions such as Iwatoyama-kofun Tumulus in Kyushu and Danpusan-kofun Tumulus in Owari.
そして、墳丘長100メートル以上の規模の比較的大きなものは九州の岩戸山古墳、尾張の断夫山古墳など一部を除くと、奈良盆地内や古市古墳群など、畿内に集中するようになる。