After the death of Nobutsuna SASAKI, most of his territory was supposed to be inherited by his third son, Yasutsuna SASAKI; however, a move accepted by the shogunate after the appeal by Nobutsuna's disinherited first-born son Shigetsuna SASAKI, whereby the territory was divided into four on behalf of all Nobutsuna's sons.
佐々木信綱の死後、所領の多くは三男の佐々木泰綱が受け継ぐはずであったが、信綱の廃嫡された長男の佐々木重綱の訴えを幕府が容れたため、領土は兄弟で四分された。