Union of Soviet Socialist Republics is the name of the original Communist dictatorship, the West's principal adversary in the post-1945 hostility of the Cold War, and a dominant force in international affairs until its collapse in 1991. The Union of Soviet Socialist Republics (USSR) was commonly known as the Soviet Union. Occupying most of the far-flung lands of the former Russian Empire in Eastern Europe and Asia, it had its capital in Moscow, the ancestral seat of the Russian emperors, or tsars. Its title alluded to the soviets, or workers' councils, of the Russian Revolution of 1917 that catapulted Vladimir Lenin and the Bolsheviks (later renamed Communists) to power. The first state the Bolsheviks established bore the name Russian Soviet Federated Socialist Republic (RSFSR). It was the largest of the many political entities of the former Russian Empire that proliferated during the Russian Civil War (1918-1921).