Dunhuang () is a county-level city in northwestern Gansu Province, Western China. According to the 2010 Chinese census, the city has a population of 186,027, though 2019 estimates put the city's population at about 191,800. Sachu (Dunhuang) was a major stop on the ancient Silk Road and is best known for the nearby Mogao Caves.

Dunhuang is situated in an oasis containing Crescent Lake and Mingsha Shan (鳴沙山, meaning "Singing-Sand Mountain"), named after the sound of the wind whipping off the dunes, the singing sand phenomenon. Dunhuang commands a strategic position at the crossroads of the ancient Southern Silk Route and the main road leading from India via Lhasa to Mongolia and southern Siberia, and also controls the entrance to the narrow Hexi Corridor, which leads straight to the heart of the north Chinese plains and the ancient capitals of Chang'an (today known as Xi'an) and Luoyang.

Administratively, the county-level city of Dunhuang is part of the prefecture-level city of Jiuquan. Historically, the city and/or its surrounding region has also been known by the names Shazhou (prefecture of sand) or Guazhou (prefecture of melons). In the modern era, the two alternative names have been assigned respectively to Shazhou zhen (Shazhou town) which serves as Dunhuang's seat of government, and to the neighboring Guazhou County.