A permanent Russian presence in Khwarezm began in 1848 with the building of Fort Aralsk at the mouth of the Syr Darya. The Empire's military superiority was such that Khiva and the other Central Asian principalities, Bukhara and Kokand, had no chance of repelling the Russian advance, despite years of fighting. Khiva was gradually reduced in size by Russian expansion in Turkestan and, in 1873, after Russia conquered the neighbouring cities of Tashkent and Samarkand, General Von Kaufman launched an attack on Khiva consisting of 13,000 infantry and cavalry. The city of Khiva fell on 28 May 1873 and, on 12 August 1873, a peace treaty was signed that established Khiva as a quasi-independent Russian protectorate.