(tӘjĭkĭstän'), officially Republic of Tajikistan, republic (2015 est. pop. 8,192,000), 55,251 sq mi (143,100 sq km), central Asia. It borders on China in the east, Afghanistan in the south, Kyrgyzstan in the north, and Uzbekistan in the west and northwest. Dushanbe is the capital and largest city. Parts of the Pamir and Trans-Alai mt. systems are in the east, and the highest peaks in the country are Ismoili Somoni Peak (24,590 ft/7,495 m) and Ibn Sina, or Lenin, Peak, also known as Kuh-i-Gamo and formerly called Kaufmann Peak (23,405 ft/7,134 m). The southeast is occupied by an arid plateau c.12,000 to 15,000 ft (3,660–4,570 m) high. The only extensive low districts are the Tajik section of the Fergana Valley in the north and the hot, dry Gissar and Vakhsh valleys in the southwest. In the Fergana Valley, there are two small exclaves of Tajikistan, one surrounded by Kyrgyzstan, the other by Uzbekistan. The Amu Darya, Syr Darya, and Zeravshan are the chief rivers and are used for…