The Sassov (also Sassow) Hasidic dynasty began with Rabbi Moshe Leib Erblich of Sassov (1745–1807), a disciple of Rabbi Dovber of Mezeritch, the disciple of the Baal Shem Tov, the founder of Hasidism.
Sasov was located in Eastern Galicia, and is now in Ukraine.
In the late 19th century, the descendants of Reb Moishe Leib of Sassov had become rabbis in other cities. The town people found themselves without a Rebbe. They approached the Sar Shalom of Belz for guidance as to whom to appoint as Rebbe. He advised them to nominate Reb Shlomo of Sassov, who became a great leader in his own merit.