The Dunhuang Academy has produced An Age of Prosperity, as Flying Apsar as Wish, a coloring book based on the deity as depicted in the Dunhuang frescoes. [Photo provided to China Daily]

Online retailer Dangdang.com alone sold about 1.5 million copies of Secret Garden, a coloring book designed with complicated patterns that aim to help people relax while they color.

"So we thought why not create a coloring book of the Mogao Grottoes," says Ding.

Previously, Dunhuang Academy published academic books on the Mogao Grottoes, and pictorial books that are very expensive.

But with the coloring books "people can learn about the grottoes by coloring. Or they can also create their own frescoes," he says.

The academy has now decided to produce more coloring books on the Buddhist figures in the grottoes and the clothing and cosmetics of the people in the frescoes.

"We chose relatively complete frescoes that represent works of each historical period－beautiful ones."

Ding likes the flying Apsaras fresco in the No 320 Cave. It's the first picture in the Apsaras book.