It originated from the younger brother of Takatsuna SASAKI, Yoshikiyo SASAKI being assigned to the post of Shugo (provincial constable) of Izumo no kuni (Izumo Province) and Oki no kuni (Oki Province).
佐々木高綱の弟佐々木義清が出雲国・隠岐国守護に任ぜられたことが起源。