Mongolian Revolution of 1911
The Mongolian Revolution of 1911 occurred when the region of Outer Mongolia declared its independence from the Manchu-led Qing China during the Xinhai Revolution. A combination of factors, including economic hardship and failure to resist Western imperialism, led many in China to be unhappy with the Qing government.
Source: Wikipedia — Mongolian Revolution of 1911 (CC BY-SA 4.0)