YINCHUAN, March 8 (Xinhua) -- Cultural relics experts have begun a program to treat water erosion in the Xumishan Grottoes dating back over 1,500 years in northwest China's Ningxia Hui Autonomous Region.

The Xumishan Grottoes, which were initially built in the late period of the Northern Wei Dynasty (386-534), have 162 caves and more than 1,000 statues on eight hills meandering about two kilometers.

Most of the caves have been closed, however, due to water erosion and implicated geological risks.

The treatment program is expected to see historical data collection and engineering surveys completed in a key cultural area in the grottoes in two years to work out restoration plans for treatment.

Located on the northern road of the eastern section of the ancient Silk Road, the Xumishan Grottoes is one of China's top ten grottoes sites. It was listed by the World Monuments Fund as one of the 100 most endangered architectural and cultural sites in the world in 2007.