In 1919 a part of Belarus under Russian rule emerged as the Byelorussian Soviet Socialist Republic (Byelorussian SSR). Soon thereafter it merged to form the Lithuanian-Byelorussian SSR. The contested lands were divided between Poland and the Soviet Union after the war ended in 1921, and the Byelorussian SSR became a founding member of the Union of Soviet Socialist Republics in 1922. In the 1920s and 1930s, Soviet agricultural and economic policies, including collectivization and five-year plans for the national economy, led to famine and political repression.