The mountain-chain which skirts the Great Plateau on the north, distinguished in these pages by the name of Elburz, broadens out after it passes the south-eastern corner of the Caspian Sea till it covers a space of nearly three degrees (more than 200 miles).

Instead of the single lofty ridge which separates the Salt Desert from the low Caspian region, we find between the fifty-fourth and fifty-ninth degrees of east longitude three or four distinct ranges, all nearly parallel to one another, having a general direction of east and west.

Broad and rich valleys are enclosed between these latitudinal ranges which are watered by rivers of a considerable size, as more especially the Ettrek and the Gurgan.

Thus a territory is formed capable of supporting a largish population, a territory which possesses a natural unity, being shut in on three sides by mountains, and on the fourth by the Caspian.

Here in Persian times was settled a people called Hyrcani; and from them the tract derived the name of Hyrcania (Vehrkana), while the lake on which it adjoined came to be known as "the Hyrcanian Sea." The fertility of the region, its broad plains, shady woods and lofty mountains were celebrated by the ancient writers.
Further to the east, beyond the low sandy plain, and beyond the mountains in which its great rivers have their source--on the other side of the "Roof of the World," as the natives name this elevated region--lay a tract unimportant in itself, but valuable to the Persians as the home of a people from whom they obtained excellent soldiers.