Saitobaru Kofun Group

　Kofun are large mounded tombs constructed during the Kofun period (middle of the 3rd to 7th centuries AD) in a range of forms, including circular burial mounds, square burial mounds, and keyhole-shaped burial mounds. In the region of 160,000 to 200,000 kofun have been confirmed throughout the Japanese archipelago. Of these, around 5,000 are keyhole-shaped burial mounds, less than 3% of all kofun.
　More than 3,600 kofun have been confirmed in Miyazaki Prefecture. Broken down by type, these comprise of 170 keyhole-shaped burial mounds, approximately 1,400 kofun with other mound shapes (circular burial mounds or square burial mounds), approximately 950 underground tunnel tombs, and approximately 1,150 tunnel tombs. These totals are only a conservative estimate, though, as it is quite likely that there are many underground tunnel tombs and tunnel tombs yet to be discovered within the prefecture.