U-Tsang is an important region covering the central and western parts of Tibetan cultural areas including some of the world’s largest watersheds such as Brahmaputra River and the western area extending past Mount Kailash and the Himalayas, and much of the vast Changtang to the north. U-Tsang was formed from two earlier polities. U encompassed the area in and around Lhasa and the Yarlung Valley in central Tibet, which Tsang consisted of the western regions of Tibet from Gyantse to the west. Traditionally, U-Tsang was known as the cradle of Tibetan civilization and the cultural, religious, economic, and political heartland of the Tibetan people. It is in the entire territory of today’s Tibetan Autonomous Region (TAR). It is important to understand the difference between Tibet and the Tibet Autonomous Region. Tibet is the entire Tibetan Plateau where Tibetans live and the TAR is a region on the southern part of the Tibetan Plateau. Tibetans from the entire Plateau travel to Lhasa, the capital city of U-Tsang for pilgrimage. The TAR is home to some of Tibet's most sacred mountains, important temples, monasteries, and historical sites.