Hōōzan Cave Tombs are located on a tuff hill on the east bank of the Iburihashi River, with an elevation of 40 meters above the river. An archaeological excavation was conducted from 1921 to 1922, during which time 26 tombs were identified. During further excavations from 1964 through 1968, this number was expanded to 77 tombs, and the total number is now estimated to be between 150 and 200 tombs, making this one of the latest sites in the Hokuriku region, and unusual for its high density of tombs in a relatively small area. Most of the tombs have an entrance vestibule and a burial chamber, which in some cases is configured to resemble the inside of a house. The larger tombs extend up to nine meters into the hillside, with a raised platform for the sarcophagus. The smaller tombs extend only three meters. Grave goods recovered include Sue ware, Haji pottery, iron swords, and various items of jewelry. From these grave goods, it is estimated that these tombs were constructed over a 150-year period from the latter half of the 6th century to the end of the 7th century.[2]
The name comes from a local legend that one of the tombs contains buried treasure hidden by the Heian periodEmperor Kazan.