The Gosannen War (後三年合戦, gosannen kassen), also known by the English translation Later Three-Year War, was fought during Japan's
Heian period in the
province of Mutsu at the far north of Japan's main island of
Honshū. Though some scholars date the war to the period of 1086 to 1089, others place it a few years earlier, lasting from 1083 to
1087. Like the
Zenkunen War that preceded it, and the various conflicts that were to follow, the Gosannen War was a struggle for power within the competing warrior clans of the time.
See more at Wikipedia.org...