Dunhuang was once an important site on the ancient Silk Road, a 2,000-year-old trade route that linked Asia and Europe, starting in Xi'an, capital of northwest China's Shaanxi province, and ending in Europe after passing through southern and central Asian countries. Surrounded by a desert, Dunhuang has an extremely arid climate and a very fragile ecosystem. Dunhuang's major sights and attractions include: Mogao Caves, Crescent Moon Lake and Singing Sand Dunes. [Photo/Sohu.com]