The same sandstone cliff that held the two giant Buddhas is honeycombed with several hundred small caves cut for use by Buddhist monks between roughly the 3rd and the 9th centuries AD. Some are simple meditation cells; others are larger assembly chambers with painted ceilings and remnants of murals. The most accessible caves are reached from the staircase between the two empty niches; many are open to visitors with a local guide.
Until 2008, when Japanese archaeologists confirmed it through pigment analysis, the cave paintings were thought to be the world's earliest known oil paintings, predating European oil painting by several centuries. Many of the murals have been damaged by water, looters, and the 2001 destruction; what survives gives a vivid sense of the cosmopolitan Buddhist culture that thrived in the valley on the Silk Road.