 Because of its strategic geographic position, the area around Morioka had been regarded as the center of northern Ōshū since the construction of nearby Shiwa Castle by the Yamato dynasty in the early Heian period.The area was later contested between the Abe clan and the Kiyohara clan in the Former Nine Years War, and it is believed that the first fortification had been erected on this site by the Kiyohara clan.The Kiyohara were destroyed by the Northern Fujiwara of Hiraizumi, who in turn were destroyed by the Minamoto clan of the Kamakura shogunate.