sentences:  After the fall of the republic, the February Uprising soon took place in 1921, and led to the establishment of the Republic of Mountainous Armenia by Armenian forces under command of Garegin Nzhdeh on 26 April, which fought off both Soviet and Turkish intrusions in the Zangezur region of southern Armenia.After Soviet agreements to include the Syunik Province in Armenia's borders, the rebellion ended and the Red Army took control of the region on 13 July.Armenia was annexed by Bolshevist Russia and along with Georgia and Azerbaijan, it was incorporated into the Soviet Union as part of the Transcaucasian SFSR (TSFSR) on 4 March 1922.