[Series 1: The role of the previous nine years and the role of the later three years] Why did the Ou War occur at the end of the Heian period...

Also known as the ``Twelve Years' Battle of Oshu,'' this battle was fought in Mutsu and Dewa, present-day Iwate and Akita prefectures, at the end of the Heian period.

Daiwa Consilio2023.11.28