A period in Japanese history, 4th-7th century AD, known for round tombs covered by a mound with a square platform off to the side, making a keyhole shape. Towards end of period, tombs were very large and surrounded by a moat, and earthenware figures and models (Haniwa) were placed in a series of concentric rings around the tomb. Inside was a chamber of stone slabs, probably adopted from cist tomb of northeast Asia. Burial goods included bronze mirrors, Chinese-type swords, magatama (fine polished stone ornaments), and Sue Ware pottery.