1919 - The Belarusian Soviet Socialist Republic is proclaimed. 1921 - The Treaty of Riga divides Belarus between Poland and Soviet Russia.1922 - The Belarusian SSR becomes founding member of the USSR. Stalin's purges1930s - Belarus suffers from the purges against intellectuals and political opponents ordered by Stalin. More than one-hundred thousand people are executed in Belarus, thousands more sent to labour camps in Siberia. 1941 - Nazi Germany invades during the course of World War II. More than one million people are killed during the occupation, including many Jews.