Xining[a] is the capital and most populous city of Qinghai province in western China[4] and the largest city on the Tibetan Plateau. As of the 2020 census, it had 2,467,965 inhabitants (2,208,708 as of 2010), of whom 1,954,795 lived in the built-up (or metro) area made of 5 urban districts.[5] The city lies in the Huangshui River Valley, also known as Tsongkha (Tibetan: ཙོང་ཁ་), and owing to its high altitude, has a cool climate on the borderline between cool semi-arid and dry winter humid continental. Xining 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 Kumbum Monastery. It is connected by the Qinghai–Tibet railway to Lhasa, Tibet and connected by a high-speed railway to Lanzhou, Gansu and Ürümqi, Xinjiang.