The Mogao Caves and the sealed library

Five hundred rock-cut temples in a cliff 25 km southeast of Dunhuang, begun in 366 when a monk called Le Zun saw a vision of a thousand Buddhas in golden light, and carved on for a thousand years while the Silk Road ran past the door. The find that matters is Cave 17. Sometime early in the eleventh century somebody walled up a side chamber, and it stayed shut until a caretaker named Wang Yuanlu opened it in 1900 and found roughly 50,000 documents inside, from the fifth to the eleventh century, in a dozen languages, including the Diamond Sutra of 868 which is the earliest dated printed book in existence. Nobody knows why it was sealed. Aurel Stein talked Wang out of about 7,000 complete manuscripts and 6,000 fragments in 1907, Paul Pelliot took nearly 10,000 more, and the library is now scattered across the museums of the world. UNESCO listed the caves in 1987 and daily numbers are capped.