Keyhole-shaped tumuli were build with regional characteristics, such as Saitama-kofun Tumuli Group with a rectangular double moat and a keyhole-shaped tumulus in Shimotsuke with a wide plane surface called kidan (a platform on which a tomb was placed).
埼玉古墳群では長方形をした二重周濠の築造、下野の前方後円墳では基壇と呼ばれる広い平坦面を持った前方後円墳など、地域色が見られる前方後円墳が造られている。