of Khiva, ruled by a branch of the Astrakhans, a Genghisid dynasty. In the 17th century Khiva began to develop as a slave market. During the first half of the 19th century, around 30000 Persians and an unknown number of Russians, were enslaved there before being sold. A large part of them were involved in the construction of buildings in the walled Ichan-Kala. Campaigns In the course of the Russian conquest of Central Asia, in 1873 the Russian General Konstantin von Kaufman launched an attack on the city of Khiva, which fell on 28 May 1873. Although the Russian Empire now controlled the Khanate, it allowed Khiva to remain as a nominally quasi-independent protectorate. Following the Bolshevik seizure of power in Russia after the October Revolution of 1917, a short-lived (1920-1925) Khorezm People's Soviet Republic formed out of the territory of the old Khanate of Khiva before its incorporation into the USSR in 1925. The city of Khiva became part of the Uzbek Soviet Socialist Republic. Sights Khiva is split into two parts. The outer town, called Dichan Kala, was formerly protected by a wall with 11 gates. The inner town, or Itchan Kala, is encircled by brick walls, whose foundations are believed to have been laid in the 10th century. Present-day crenellated walls date back to the late 17th century and attain the height of 10 meters. Kalta Minor, the large blue tower in the central city square, was supposed to be a minaret. It was built in 1851 by Mohammed Amin Khan, but the Khan died and the succeeding Khan did not complete it. The old town retains more than 50 historic monuments and 250 old houses, mostly dating from the 18th or the 19th centuries. Djuma Mosque, for instance, was established in the 10th century and rebuilt in 1788–89, although its celebrated hypostyle hall still retains 112 columns taken from ancient structures. Khiva was a home to a number of madrassahs (educational establishments), one of which, Sherghazi Khan madrassah, still stands today. It was built in the 18th century by slaves and is one of the oldest buildings in Ichan-Kala, that is the center of present-day Khiva. Among the renowned students of the madrassah were the Uzbek poet Raunaq, the Qaraqalpaq poet Kasybayuly, the Turkmen poet and sufi Magtymguly. Notable people from Khiva The following people were born in the city. Tamara Abaeva (born 1927), historian. Sayid