 The large scale of these settlements revolutionized theories on Jōmon period civilization.During the Heian period, the area was part of the holdings of the Northern Fujiwara clan, but remained inhabited by the Emishi people well into the historic period.After the fall of the Northern Fujiwara in the Kamakura period, the territory was part of the domain assigned to the Nambu clan, and into the Sengoku period, it came under the control of the rival Tsugaru clan, whose main castle was located in Namioka.