But in the upland country the heat is at no time very intense, and the natives boast that they are not compelled by it to sleep on their house-tops during more than one month in the year.
The countries by which Parthia Proper was bounded were the following: Chorasmia, Margiana, Aria, Sarangia, Sagartia, and Hyrcania.
Chorasmia lay upon the north, consisting of the low tract between the most northerly of the Parthian mountain chains and the old course of the Oxus.

This region, which is for the most part an arid and inhospitable desert, can at no time have maintained more than a sparse and scanty population.

The Turkoman tribes which at the present day roam over the waste, feeding their flocks and herds alternately on the banks of the Oxus and the Tejend, or finding a bare subsistence for them about the ponds and pools left by the winter rains, represent, it is probable, with sufficient faithfulness, the ancient inhabitants, who, whatever their race, must always have been nomads, and can never have exceeded a few hundred thousands.

On this side Parthia must always have been tolerably safe from attacks, unless the Cis-Oxianian tribes were reinforced, as they sometimes were, by hordes from beyond the river.
On the north-east was Margiana, sometimes regarded as a country by itself, sometimes reckoned a mere district of Bactria.

This was the tract of fertile land upon the Murg-ab, or ancient Margus river, which is known among moderns as the district of Merv.