When MINAMOTO no Yoritomo raised his army in the Kanto region, the Omi Sasaki clan took part in it positively and gained Omi shugoshiki (provincial constables of Omi Province).
この佐々木氏は、源頼朝が関東地方で勃興するとこれに積極的に加わり、近江一国の守護職を得た。