A cultural relics protection personnel of the Dunhuang Academy China repairs the murals in Cave 130 of the Mogao Grottoes. [PHOTO BY SUN ZHIJUN/CHINA DAILY]

Although the Mogao Grottoes area is large and the caves numerous, the size of each cave is extremely small. More than 85 percent of the caves are less than 25 square meters. And many of the colored sculptures and murals are made of fragile materials such as dirt, wood and wheat straw. So, if 15 people remain in a cave for more than 10 minutes, the temperature in the cave will increase by 5 C, and the concentration of carbon dioxide increases greatly.

This means that a large number of tourists will inevitably accelerate the aging of the murals and colorful sculptures.

The Mogao Grottoes are the highlight of Dunhuang, but Dunhuang has more to offer.