무쓰 국
After 718, and the widening influence of the Yamato Imperial Court, Mutsu Province was expanded northwards into present-day Miyagi Prefecture. Along with this redrawing of boundaries, present-day Fukushima Prefecture was separated from the new Mutsu Province (approximately present-day Miyagi) and split between the newly formed provinces of Iwaki in the east and Iwase in the west. However, by 724 Mutsu Province was unable to deal on its own with the economic costs of holding back the Emishi, so Iwaki and Iwase provinces were merged back into Mutsu.