The Soviet Union (or more formally USSR – the Union of Soviet Socialist Republics) was established in 1922 as a federation of nationalities, which eventually came to encompass 15 major national territories, each organized as a Union-level republic (Soviet Socialist Republic or SSR).
The Soviet Union (officially known as the USSR – the Union of Soviet Socialist Republics) was founded in 1922 as an alliance of ethnic groups that would eventually include 15 significant national areas, each governed as a Union-level republic (Soviet Socialist Republic or SSR).