The nomads of central Asia, who had produced great conquerors in the distant past, were little match for the disciplined armies of the 19th century. Raids by Muslim guerillas encouraged local Russian governors to take the initiative in subduing the central Asian khanates of Khiva and Bukhara. Envoys from Russia and Britain to Bokhara were treated with arrogance and contempt, and in 1848 two British officers were imprisoned and killed. In the early 1860s the Bukharans managed to fend off Russian advances, but in May 1866 they were defeated. The Russians then established a governor-general of Turkestan, on Syr Darya. The war resumed in 1868, when the Emir was forced to accept vassal status.
Malikov A., The Russian conquest of the Bukharan Emirate: military and diplomatic aspects in Central Asian Survey, Volume 33, Issue 2, 2014, pp. 180-198.
Russian Empire
Emirate of Bukhara