  This paper presents an analysis of the star atlas included in the medieval
Chinese manuscript (Or.8210/S.3326), discovered in 1907 by the archaeologist
Aurel Stein at the Silk Road town of Dunhuang and now held in the British
Library. Although partially studied by a few Chinese scholars, it has never
been fully displayed and discussed in the Western world. This set of sky maps
(12 hour angle maps in quasi-cylindrical projection and a circumpolar map in
azimuthal projection), displaying the full sky visible from the Northern
hemisphere, is up to now the oldest complete preserved star atlas from any
civilisation. It is also the first known pictorial representation of the
quasi-totality of the Chinese constellations. This paper describes the history
of the physical object - a roll of thin paper drawn with ink. We analyse the
stellar content of each map (1339 stars, 257 asterisms) and the texts
associated with the maps. We establish the precision with which the maps are
drawn (1.5 to 4 degrees for the brightest stars) and examine the type of
projections used. We conclude that precise mathematical methods were used to
produce the atlas. We also discuss the dating of the manuscript and its
possible author and confirm the dates 649-684 (early Tang dynasty) as most
probable based on available evidence. This is at variance with a prior estimate
around +940. Finally we present a brief comparison with later sky maps, both in
China and in Europe.
