The Occupation of Outer Mongolia by the Beiyang government of the Republic of China after the revocation of Outer Mongolian autonomy began in October 1919 and lasted until 18 March 1921, when Chinese troops in Urga were routed by Baron Roman von Ungern-Sternberg's White Russian and Mongolian forces. These, in turn, were defeated by the Red Army and its Mongolian allies by June 1921. Although the Beiyang government abolished the autonomy of the Bogd Khanate of Mongolia in Outer Mongolia and then expanded its occupation to include Uryankhay Krai, it was unable to consolidate its rule over both regions.