Satomi clan
Most of the Bōsō Peninsula was controlled by the powerful Satomi clan during the Sengoku period. The Satomi fought numerous battles with the Later Hōjō clan of Odawara for control of the Kantō region. In 1580, Satomi Yoriyoshi built Tateyama Castle in southern Awa Province to guard the southern portion of his territories and increase his control over the entrance to Edo Bay. The castle of rebuilt by his son, Satomi Yoshiyasu in 1588.