was an old province of Japan in the area of Fukushima, Miyagi, Iwate and Aomori Prefectures and the municipalities of Kazuno and Kosaka in Akita Prefecture.
Mutsu Province is also known as Ōshū or Michinoku. The term Ōu is often used to refer to the combined area of Mutsu and the neighboring province Dewa, which together make up the entire Tōhoku region.
Mutsu, on northern Honshū, was one of the last provinces to be formed as land was taken from the indigenous Emishi, and became the largest as it expanded northward. The ancient regional capital of the Kinai government was Tagajō in present-day Miyagi Prefecture.
709 (Wadō 2, 3rd month), an uprising against governmental authority took place in Mutsu and in nearby Echigo Province. Troops were dispatched to subdue the revolt.
712 (Wadō 5), Mutsu was separated from Dewa Province. Empress Genmei's Daijō-kan made cadastral changes in the provincial map of the Nara period, as in the following year when Mimasaka Province was split from Bizen Province, Hyūga Province was sundered from Ōsumi Province, and Tanba Province was severed from Tango Province.
718, Shineha, Uda and Watari districts of the Mutsu Province, Kikuta, Iwaki districts of the Hitachi Province are incorporated into Iwaki Province (718).
801, Mutsu was conquered by Sakanoue no Tamuramaro.
869 (Jōgan 10, 5th month): A terrible earthquake struck Mutsu. More than 1,000 people lost their lives in the disaster.
In 1095, the Ōshū Fujiwara clan settled at Hiraizumi, under the leadership of Fujiwara no Kiyohira. Kiyohira hoped to "form a city rivaling Kyoto as a centre of culture". The legacy of the Ōshū Fujiwara clan remains with the temples Chūson-ji and Mōtsū-ji in Hiraizumi, and the Shiramizu Amidadō temple building in Iwaki. In 1189, Minamoto no Yoritomo invaded Mutsu with three great forces, eventually killing Fujiwara no Yasuhira and acquiring the entire domain.
During the Sengoku period, clans ruled parts of the province.
The Nanbu clan at Morioka in the north.
The Date clan at Iwadeyama and Sendai in the south.