his empire with a rich Perso-Islamic culture. During his reign and the reigns of his immediate descendants, a wide range of religious and palatial construction masterpieces were undertaken in Samarkand and other population centres. Amir Timur initiated an exchange of medical discoveries and patronised physicians, scientists and artists from the neighbouring regions such as India; His grandson Ulugh Beg was one of the world's first great astronomers. It was during the Timurid dynasty that Turkic, in the form of the Chaghatai dialect, became a literary language in its own right in Transoxiana, although the Timurids were Persianate in nature. The greatest Chaghataid writer, Ali-Shir Nava'i, was active in the city of Herat (now in northwestern Afghanistan) in the second half of the 15th century. The Timurid state quickly split in half after the death of Timur. The chronic internal fighting of the Timurids attracted the attention of the Uzbek nomadic tribes living to the north of the Aral Sea. In 1501, the Uzbek forces began a wholesale invasion of Transoxiana. The slave trade in the Khanate of Bukhara became prominent and was firmly established. Before the arrival of the Russians, present Uzbekistan was divided between Emirate of Bukhara and khanates of Khiva and Kokand. In the 19th century, the Russian Empire began to expand and spread into Central Asia. There were 210,306 Russians living in Uzbekistan in 1912. The "Great Game" period is generally regarded as running from approximately 1813 to the Anglo-Russian Convention of 1907. A second, less intensive phase followed the Bolshevik Revolution of 1917. At the start of the 19th century, there were some separating British India and the outlying regions of Tsarist Russia. Much of the land between was unmapped. In the early 1890s, Sven Hedin passed through Uzbekistan, during his first expedition. By the beginning of 1920, Central Asia was firmly in the hands of Russia and, despite some early resistance to the Bolsheviks, Uzbekistan and the rest of Central Asia became a part of the Soviet Union. On 27 October 1924 the Uzbek Soviet Socialist Republic was created. From 1941 to 1945, during World War II, 1,433,230 people from Uzbekistan fought in the Red Army against Nazi Germany. A number also fought on the German side. As many as 263,005 Uzbek soldiers died in the battlefields of the Eastern Front, and 32,670 went missing in action. On 20 June 1990, Uzbekistan declared its state