The Sannai-Maruyama Site has been well-known since Edo Period (1603–1868).The excavation which began in 1992 revealed a large settlement from the Early and Middle Jomon Period (approx. 3,900 to 2,200 B.C. and 5,900 to 4,200 B.C.). Many pit dwellings, pillar-supported buildings, mounds, and burial pits and jars were unearthed along with numerous pieces of pottery and stone implements, precious wooden objects, and bone and antler ornaments.Given the significance of the site, Aomori Prefecture decided in 1994 to take up responsibility for the preservation of Sannai-Maruyama and in November 2000, it was registered as a special national historic site. A free guide tour is on offer by volunteer guides from the Sannai-Maruyama support team.