After the Gosannen War was suppressed, the Oshu-Fujiwara clan became the effective ruler of Ou region and the position of kokushi of Mutsu Province became more like a revenue agent.
後三年の役が平定された後は、奥州藤原氏が奥羽一帯の実質的な支配者となり、陸奥国司は徴税官的側面が強くなった。