A staff member cleans an ancient document at the ancient documents protection center of Tibet in Lhasa, southwest China's Tibet Autonomous Region, Sept. 12, 2019. Since 2010, over 18,000 ancient documents in Tibet have been registered, with 291 ancient books being listed as national rare antique books. More than 3,000 pages of ancient documents from Paingar and Mangra monasteries have been restored. (Xinhua/Jigme Dorje)