On 4 July 1928, the founding congress of the Sybiraks' Association was held at the Warsaw University of Technology.
The Union of Soviet Socialist Republics was the first communist state in history. The decision to create it was taken on 30 December 1922.
On 18 March 1921, the treaty ending the Polish-Bolshevik war (the so-called Treaty of Riga) was signed in Riga.