[1] The Gosannen War was part of a long struggle for power within the warrior clans of the time.

The Gosannen kassen arose because of a series of quarrels within the Kiyohara clan (sometimes referred to as "Kiyowara").

When Minamoto no Yoshiie, who became Governor of Mutsu province in 1083, tried to calm the fighting which continued between Kiyohara no Masahira, Iehira, and Narihira.

[2] During the siege of Kanezawa, 1086–1089, Yoshiie avoided an ambush by noticing a flock of birds take flight from a forest.

[3][4] Much of the war is depicted in an e-maki narrative handscroll, the Gosannen kassen emaki, which was created in 1171.