The plain of Chinese Tartary, the district about Kashgar and Yarkand, seems to have been in possession of certain Sacans or Scythians, who in the flourishing times of the empire acknowledged subjection to the Persian crown.

These Sacans, who call themselves Huma-varga or Amyrgians, furnished some of the best and bravest of the Persian troops.

Westward they bordered on Sogdiana and Bactria; northward they extended probably to the great mountain-chain of the Tien-chan; on the east they were shut in by the vast desert of Gobi or Shamoo; while southward they must have touched Gandaria and perhaps India.

A portion of this country--that towards the north and west--was well watered and fairly productive; but the southern and eastern part of it must have been arid and desert.
From this consideration of the Eastern provinces of the Empire, we pass on naturally to those which lay towards the North-West.

The Caspian Sea alone intervened between these two groups, which thus approached each other within a distance of some 250 or 260 miles.
Almost immediately to the west of the Caspian there rises a high table-land diversified by mountains, which stretches eastward for more than eighteen degrees between the 37th and 41st parallels.