On the west, approaching generally within twenty or thirty miles of the present course of the Euphrates, is the Arabian Desert, consisting in this place of tertiary sand and gravels, having a general elevation of a few feet above the Mesopotamian plain, and occasionally rising into ridges of no great height, whose direction is parallel to the course of the great stream.

Such are the Hazem and the Qassaim, in the country between the Bahr-i-Nedjif and the Persian Gulf, low pebbly ridges which skirt the valley from the Bahr to below Suk-es-Sheioukh.

Further west the desert becomes more stony, its surface being strewn with numerous blocks of black granite, from which it derives its appellation of Hejerra.

No permanent streams water this region; occasional "wadys" or torrent-courses, only full after heavy rains, are found; but the scattered inhabitants depend for water chiefly on their wells, which are deep and numerous, but yield only a scanty supply of a brackish and unpalatable fluid.

No settled population can at any time have found subsistence in this region, which produces only a few dates, and in places a poor and unsucculent herbage.