Xining is the capital of Qinghai province in western China, and the largest city on the Tibetan Plateau. It has 2,208,708 inhabitants at the 2010 census whom 1,198,304 live in the built up area made of 4 urban districts.The city was a commercial hub along the Northern Silk Road's Hexi Corridor for over 2000 years, and was a stronghold of the Han, Sui, Tang, and Song dynasties' resistance against nomadic attacks from the west. Although long a part of Gansu province, Xining was added to Qinghai in 1928. Xining holds sites of religious significance to Muslims and Buddhists, including the Dongguan Mosque and Ta'er Monastery. The city lies in the Huangshui River valley, and owing to its high altitude, has a cold semi-arid climate. It is connected by rail to Lhasa, Tibet and Lanzhou, Gansu.