During the late Sengoku period, Nanbu Nobunao pledged fealty to Toyotomi Hideyoshi at the Siege of Odawara in 1590 was confirmed as "daimyō" over all of the Nanbu territories, including lands around the site the site of old Kozukata Castle in Morioka. He decided to move his seat south from its former location at Sannohe Castle and to erect a new castle at Morioka. The design of the new castle may have been influenced by Nagoya Castle in Hizen Province, which he saw during the Japanese invasions of Korea. His holdings were re-confirmed after the Battle of Sekigahara by Tokugawa Ieyasu, and Morioka remained the seat of the Nanbu clan until the Meiji Restoration.