Khotan 

A small early medieval oasis state on the southen route of the Silk Road which became an important centre and staging-post for Buddhism by the 2nd century ce. As Buddhism became established here, both Hīnayāna and Mahāyāna monastic establishments were founded. The dry climate of the area has resulted in the preservation of fragments of Buddhist manuscripts and some important early paintings and murals.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)