54 THE REGIONS SURVEYED [Chap. II
northern slopes of the mountains. The physical conditions here observed present a very striking contrast to those found in the Turfân basin just across the range.
This sudden change is particularly impressive owing to the close connection which, faci
litated by several direct passes practicable during the greater part of the year, has been maintained with the flourishing oases of that basin throughout historical times. 10 We have seen that the Turfân district
reproduces on a small scale all the typical features of the Tarim basin. Hence the inclusion in the same map sheet, No. 28, which represents its topography, of this edge of Dzungaria, a specimen, as it were, of another vast division of Central Asia, cannot fail to be geographically instructive.
Turf an basin.
10 The closeness of the relations, political as well as economic, which have always linked Turf iin with the territory in the north, known to the Chinese administration of T'ang times (7th-8th century e. D.) as the Protectorate of Pei.t'ing and under the Mongols as Bish-batik, the Five Towns', is illustrated by
the significant fact that the earliest historical records, contained in the Annals of the Han dynasty and dating from the first centuries before and after Christ, distinguish them only as ' Anterior' and ' Posterior S'u-shih'; cf. Chavannes, in T'oung.pao, 1907, pp. 210 sq.