One of the Kansai (Kinki) region's major mound groups. Yao City reports 230 surviving mounds, while the Agency for Cultural Affairs gives 224 confirmed at the time of designation. The National Historic Site does not cover the whole group: an area of 110 mounds centred on the Hattorigawa subgroup was designated in 2015, and Korigawa Nishizuka Kofun, about 1km to the west, and other areas were added in 2021.
Finds & research
Korean-style pottery and miniature cooking sets suggest connections with immigrant-derived communities. A pointed-pommel sword, earrings, and Sue ware are traditionally attributed to Moritayama Kofun in the Hattorigawa subgroup.
Official status & archaeological view
Official status
An area centred on the Hattorigawa subgroup, containing 110 mounds and about 63,740 square metres, was designated a National Historic Site on 10 March 2015; Korigawa Nishizuka Kofun and parts of Hattorigawa Mounds 12, 22 and 59 were added to the designation on 11 October 2021.
Archaeological view
A large mound group on the slopes of Mount Takayasu in eastern Yao, built from the 6th to the first half of the 7th century and peaking in the late 6th. Taisho-era records list 565 mounds; Yao City's 2025 account says 230 survive. Nearly all are round mounds with horizontal stone chambers, usually three to five tatami mats in floor area, though five are nine mats or larger.
Field notes
Many mounds survive among woodland and plant nurseries, mostly on private land. Use the mounds open to visitors as guided by Yao City's booklet (with walking map), and do not enter private land or chambers not covered by the guide.