It is the war against Ezo/Emishi (the generic name of the native people living in the north part of Japan) by the troops led by MINAMOTO no Yoritoshi, the goovernor of Mutsu Province, and KIYOHARA no Sadahira ("清原貞衡" Studies suggest this Sadahira is the same person with "清原真衡") during the Eikyu era from 1069 to 1074.
西暦1069年から1074年までの延久年間に、陸奥守源頼俊が清原貞衡（清原真衡と同一人物との有力説がある）と共に兵を率い蝦夷を攻略したとされる戦い。