What people get wrong about Dunhuang manuscripts.

In the year 1900, a Taoist caretaker sweeping the Buddhist cave temples of Dunhuang, in the desert of western China, noticed a crack in a corridor wall — and behind it, a small cave packed floor to ceiling with ancient manuscripts. It had been sealed for nearly a thousand years. Inside were some 50,000 documents: sutras, letters, star charts, contracts, love poems, and homework exercises — the entire paper trail of the Silk Road, frozen in time. It is called the Library Cave, and its opening is one of the great archival discoveries in history.

The caretaker was Wang Yuanlu, a self-appointed guardian of the Mogao Caves — 735 hand-carved temple grottos honeycombing a cliff face, built and painted over a thousand years starting in the 4th century. Cave 17, the Library Cave, was tiny, barely three meters square, but someone around the year 1000 CE had filled it with manuscripts and walled it up. Why? Nobody knows for certain. Perhaps to protect the scriptures from invaders; perhaps it was a ritual burial of worn-out sacred texts, which Buddhist custom forbade destroying; perhaps the monks simply ran out of room. Whatever the reason, the desert’s dry air did the rest, preserving paper that would have crumbled to dust anywhere else.

Wang Yuanlu tried to interest Chinese officials, who were too distracted by a collapsing dynasty to care. Then the foreigners arrived. In 1907, the Hungarian-British archaeologist Aurel Stein — already famous for his Central Asian expeditions — talked the hesitant Wang into selling him thousands of manuscripts for a small sum, carting away seven thousand complete texts and fragments. The next year, the French scholar Paul Pelliot, who actually read Chinese, spent three weeks in the cave in a frenzy of selection, taking the finest items — including, as it happened, the Diamond Sutra, the world’s oldest dated printed book. Russian, Japanese, and later Chinese expeditions took more. Within a few decades, the Library Cave was empty, its contents scattered across London, Paris, Beijing, and St. Petersburg.

What those documents contained rewrote the history of the Silk Road. There were Buddhist sutras in Chinese, Tibetan, Sanskrit, and lost Central Asian languages; there were also Nestorian Christian texts, Manichaean scriptures, and Jewish prayers — proof that Dunhuang was a crossroads of every faith moving along the trade routes. There were government tax records, military dispatches, medical manuals, calendars, divination guides, and personal letters — including the voice of ordinary people: a student’s complaint about his teacher, a contract for the sale of a slave, a love poem. The world’s oldest printed star chart, from around 700 CE, came from the cave. So did the earliest known printed almanacs.

The dispersal remains a wound in China, where Stein and Pelliot are still reviled as thieves — though some historians note the manuscripts might not have survived the wars and upheavals of 20th-century China had they stayed. Today the International Dunhuang Project is digitally reuniting the collection, photographing every fragment in high resolution so scholars can study together what politics keeps apart.

The Library Cave is a time capsule with no parallel: a single room, sealed in the year 1000, holding the paperwork of the most cosmopolitan trade route in human history. A monk swept a corridor, noticed a crack, and opened a window onto a thousand years.