The Dunhuang Chinese Sky, a set of sky maps drawn on a roll of thin paper, displaying the full sky visible from the Northern hemisphere, included in the medieval Chinese manuscript (Or. 8210/S.3326) preserved in the British Library, is the oldest known star atlas. It was discovered in 1907 by the archaeologist Aurel Stein in the Mogao Caves, also known as The Caves of the Thousand Buddhas, in Dunhuang, a town on the northern Silk Road, in Gansu province, China. The earliest later star atlases in China date from the eleventh century.
The Dunhuang star atlas, drawn in two inks on fine paper and remarkably well preserved, represents more than 1300 individual stars in the total sky as could be seen with the naked eye from the Chinese imperial observatory along with an explanatory text. It displays the sky "as in the most modern charts with twelve hour-angle maps, plus a North polar region."
"It was discovered by the British-nationalised but Hungarian-born archaeologist Aurel Stein in 1907 among the pile of at least 40,000 manuscripts enclosed in the so-called Library Cave (Cave 17) in the Mogao ensemble, also known as the ‘Caves of the Thousand Buddhas’ near Dunhuang (Gansu). The Mogao caves are a set of several hundred Buddhist temples cut into a cliff and heavily decorated with statues and murals. The site was active from about +3602 to the end of the Mongol period. In about +1000, one cave was apparently sealed (Rong Xinjiang, 1999) to preserve a collection of precious manuscripts and some printed material including the world’s earliest dated complete printed book . The sealed cave was rediscovered by accident and re-opened only a few years before the arrival of Stein in 1907. He was therefore the first European visitor to see the hidden library" (Bonnet-Bidaud, Praderie & Whitfield, The Dunhuang Chinese Sky: A Comprehensive Study of the Oldest Known Star Atlas  2).