XINING, China -- Experts in China have restored a 700-year-old copy of the Koran, the sacred book of Islam.

The state-run news agency Xinhua reported that the two-volume, 867-page set is the oldest known in China and is written in Arabic.

The ancient copy of the Koran is believed to have been brought to China about 700 years ago when the Salar ethnic group moved east from Uzbekistan. Experts believe it was written some time between the eighth and 13th centuries.

Because the book is handwritten by Arabian Muslims, it is believed to be of great value as a research tool. All other ancient copies of the Koran that exist in China were written by Chinese Muslims, Xinhua reported.