Lenin and his aides form the Soviet Union, by joining the Russian SFSR into a single state with the Byelorussian, Transcaucasian, and Ukrainian republics, on December 30, 1922.
Eventually internal border changes and annexations during the second World War will create a union of fifteen republics; the largest in size and population being the Russian SFSR, which will dominate the union for its entire history politically, culturally, and economically.