A mural fragment dating to the Northern Liang kingdom (397-439) from the Tiantishan Grottoes in Gansu province. [Photo provided to China Daily]

In 1959, construction of a dam was planned in front of Tiantishan Grottoes. To save the murals from possible inundation, they were all relocated to Lanzhou, capital of Gansu province. There, a piece of Northern Liang kingdom mural was found beneath the repainted surface done centuries later.

According to Liu Zhi, director of Tiantishan Grottoes Protection and Research Institute, during restoration of the relocated mural pieces from 2015 to last year, several more Northern Liang murals have been discovered. The relocated murals have now returned to Wuwei.

"The flying deities (called feitian in Chinese) in these murals sometimes feel 'clumsy', compared with the exquisite fairy-like images in later periods of history," Liu says. "But their coloring, lines, shading, and expression of emotions are indeed of very high skill. They perfectly reflect the artistic style of Buddhist art in its earliest stage."