 Nanbu Mitsuyuki was awarded vast estates in Nukanobu District after he had joined Minamoto no Yoritomo at the Battle of Ishibashiyama and the conquest of the Northern Fujiwara.Nanbu Mitsuyuki built Shōjujidate Castle in what is now Nanbu, Aomori.The eastern area of the current prefecture was dominated by horse ranches, and the Nanbu grew powerful and wealthy on the supply of warhorses.