Map 27.1 The Formation of the U.S.S.R. When the Bolsheviks successfully overthrew the tsarist government and won the civil war that followed, they inherited the vast territories of the former Russian empire. Following policies instituted by Stalin, they established a Union of Soviet Socialist Republics (U.S.S.R.) that gave limited cultural independence but no real political autonomy to the various Soviet republics under Communist control.