March 13, 1921: Provisional Government declares independence of Mongolia
Spring-Summer 1921: Suhbaatar with help of the Red Army defeats Ungern's forces in Mongolia
May 31, 1924: U.S.S.R. signs agreement with Peking government, referring to Inner Mongolia as an "integral part of the Republic of China," whose "sovereignty" therein the Soviet Union promises to respect.
May-September 16, 1939: Large scale fighting takes place between Japanese and Soviet-Mongolian forces along Khalkhyn Gol on Mongolia-Manchuria border (Battle of Halhin Gol), ending in defeat of the Japanese expeditionary force. Truce negotiated between U.S.S.R. and Japan.