March 13, 1921: Provisional People's Government declares independence of Mongolia.
May 31, 1924: U.S.S.R signs agreement with Peking government, referring to Outer 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, ending in defeat of the Japanese expeditionary force. Truce negotiated between U.S.S.R. and Japan.
October 6, 1949: Newly established People's Republic of China accepts recognition accorded Mongolia and agrees to establish diplomatic relations.