869 (Jōgan 10, 5th month): An earthquake and tsunami caused more than 1,000 deaths.
1051 (Eishō 6): In Michinoku, the Nine Years War (1051–1062) begins. Minamoto no Yoriyoshi is named governor of Mutsu and he is given the title chinjufu shōgun..
In the Meiji period, the provinces of Japan were converted into prefectures. Maps of Japan and Mutsu Province were reformed in the 1870s.