The Chinese occupation of Mongolia from 1919 to 1921 had significant impacts:
Revocation of Autonomy: The Beiyang government of the Republic of China revoked Outer Mongolia's autonomy, initiating the occupation in October 1919.
Military Presence: Chinese troops entered and took control of key areas, including the capital, Urga (now Ulaanbaatar).
Resistance and Expulsion: Mongolian forces, allied with White Russian troops led by Baron Roman von Ungern-Sternberg, initially managed to expel Chinese forces in March 1921. However, these forces were later defeated by the Red Army and its Mongolian allies by June 1921.
Restoration of Independence: Mongolia proclaimed its independence on July 11, 1921. The People's Government took charge, with the Bogd Khan serving as a symbolic monarch.
For more detailed reading, you can refer to the sources such as Wikipedia and Penn Museum.
What were the main causes of the Red Flag riots in 1919 in Brisbane?
What eventually happened to Burnside Distillery after it stopped production in 1919?
Which manager served in both 1907-1911 and 1919-1923 periods for AC Sparta Prague?
Which art exhibitions did Emmy Lischke participate in between 1917 and 1919?