The Mori clan, who settled in the Aki Province as kokujin (lords of smaller rural domains in feudal Japan), produced several branch families, although some families fought each other during the middle of the Muromachi period, they became one of the most powerful families in the province.
安芸国の国人として土着した毛利氏は、一族庶家を輩出し、室町時代中期には庶家同士の争いが起きたものの、安芸国内では屈指の勢力になった。