Mongolian Revolution of 1921

The Mongolian Revolution of 1921, locally known as the People's Revolution of 1921, was a military and political event by which Mongolian revolutionaries, with the assistance of the Soviet Red Army, expelled Russian White Guards from the country, and founded the Mongolian People's Republic in 1924. Although nominally independent, the Mongolian People's Republic was a satellite state of the Soviet Union until the democratic revolution in January 1990.

Source: Wikipedia — Mongolian Revolution of 1921 (CC BY-SA 4.0)