Visitors look at items on display at the Dunguang grotto art exhibition in Chengdu, Dec 26, 2016. [Photo/Xinhua]

As a major stop along the Silk Road, the Dunhuang Mogao Caves in Northwest China's Gansu province hold China's largest collection of stone carvings and mural paintings. It contains valuable information about religion, culture, and social life in ancient China from the 4th to the 14th century.