Tarim (dārēmˈ) [key], Mandarin Dayan, chief river of Xinjiang Uygur Autonomous Region, NW China, c.1,300 mi (2,090 km) long, formed by the union of the Aksu and the Yarkant rivers at the western end of the Taklimakan desert, and flowing generally east, along the northern edge of the desert, to Lop Nur, a largely dried-up salt lake. Kashi (Kashgar) is the region's largest city. The river, which is silt-laden, gives its name to the arid Tarim basin, a great depression, c.800 mi (1,290 km) long and 400 mi (640 km) wide, surrounded by the lofty Tian Shan, Kunlun, and Pamir mountains; the Taklimakan occupies most of the basin. Over 50% of Xinjiang's population live in the basin's oases. China's nuclear-testing center is located at the eastern end of the Tarim basin, near Lop Nur. Archaelogical excavations at ancient sites in the region dating from 2,000 to 4,000 years old have revealed the mummified remains of people with Caucasian features. DNA research indicates that these early inhabitants may be of mixed European and Siberian descent, and linguists have speculated that they spoke Tokharian, an extinct Indo-European language known from surviving inscriptions. The important Silk Road between China and Europe passed through the basin.