December 30: On December 30, 1922, the Union of Soviet Socialist Republics was formed.

The Soviet Union had a one-party political system dominated by the Communist Party until 1990, and although it was a federal union of 15 subnational Soviet republics, the Soviet state was structured under a national government and a highly centralized economy.

Lenin speaking at an assemble of Red Army troops bound for the Polish front. Photograph taken in Sverdlov Square, Moscow, on 5 May 1920. This is the original photo with Trotsky and Kamenev standing on the steps of the platform; later versions produced under Stalin's administration had them removed.

The Russian revolution of 1917 that brought down the Russian Empire had as successor to the Russian Provisional Government, which was short-lived, because the Bolsheviks won the Russian Civil War and founded the Soviet Union in December 1922 with the merger of the Russian Soviet Federative Socialist Republic, Russian Soviet Federal Socialist Republic of Transcaucasia, the Ukrainian Soviet Socialist Republic, and the Byelorussian Soviet Socialist Republic.

The Russian republic was by far the largest of the 15 republics.

After the death of the first Soviet leader, Vladimir Lenin, in 1924, Joseph Stalin eventually won the struggle for poder and led the country through a large-scale industrialization, with a centralized economy and extreme political repression. In June 1941, during World War II, Germany invaded the Soviet Union, a country with which it had signed a non-aggression pact. After four years of brutal warfare, the Soviet Union emerged victorious as one of the world's two superpowers, along with the United States.

The Soviet Union and its Eastern European allies were involved in the Cold War, which was a prolonged global ideological and political struggle against the United States and its allies of the Western bloc; USSR finally yielded to the economic problems and internal and externos. during this period political unrest, the Soviet Union became the reference model for future socialist states.

From 1945 to 1991, the Soviet Union and the United States dominated the global agenda of economic policy, foreign affairs, military operations, cultural exchange, scientific progress including the initiation of space exploration, and sports (including the Olympic Games). In the late 1980s, the last Soviet leader Mikhail Gorbachev tried to reform the state with his policies of perestroika and glasnost, but the Soviet Union collapsed and was formally dissolved in December 1991 after the failed coup of agosto. After that, the Russian Federation assumed its rights and obligations.