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 autonomy but no real political independence to the Soviet republics now under Communist control.