The Russian Soviet Federative Socialist Republic (Russian SFSR or RSFSR; ), previously known as the Russian Soviet Republic and the Russian Socialist Federative Soviet Republic as well as being unofficially known as Soviet Russia, Russian Federation or simply Russia, was an independent socialist state from 1917 to 1922. Afterwards it was the largest and most populous of the Soviet socialist republics of the Soviet Union (USSR) from 1922 to 1991. 