In this neighborhood alone are found the geographic names which the most ancient writers who mention the Parthians connect with them.

Here evidently the Parthians were settled at the time when Alexander the Great overran the East, and first made the Greeks thoroughly familiar with the Parthian name and territory.

Here, lastly, in the time of the highest Parthian splendor and prosperity, did a province of the Empire retain the name of Parthyene, or Parthia Proper; and here, also, in their palmiest days, did the Parthian kings continue to have a capital and a residence.
Parthia Proper, however, was at no time coextensive with the region described.

A portion of that region formed the district called Hyrcania; and it is not altogether easy to determine what were the limits between the two.

The evidence goes, on the whole, to show that, while Hyrcania lay towards the west and north, the Parthian country was that towards the south and east, the valleys of the Ettrek and Gurghan constituting the main portions of the former, while the tracts east and south of those valleys, as far as the sixty-first degree of E.longitude, constituted the latter.
If the limits of Parthia Proper be thus defined, it will have nearly corresponded to the modern Persian province of Khorasan.