Its plains present greater variety in extent and direction and elevation, but are all alike in general character—equally arid, equally void of trees, and equally covered with pasture plants. All are more or less the resort of nomads with their flocks and herds, and some are peopled by fixed communities settled in villages. I will now describe each of these points in the physical geography of this region separately, but time and space only permit of my doing so very briefly and in general terms. As before indicated, the region between the valleys of the Indus and the Tigris is an elevated country, propped up on all sides by great mountain ranges. On the east, it is separated from the valley of the Indus by the Sulemán range, which continues southwards to the sea-coast in the Hala mountains that separate Balochistan from Sind. To the northward it connects, through the Sufed Koh of Kabul, with the Kohi Baba of Hindu Kush. This range contains within its ridges many fertile valleys and small plains, all of which drain eastwards to the Indus. To its west lies the high tableland of Ghazni, and Kandahar and Balochistan. On the west, it is separated from the valley of the Tigris by the range of the Zagros mountains, which northwards, through the hills of Kurdistan, unite with the Armenian mountains. To the southward it extends by the mountains of Laristan and Khuzistan to those forming the southern boundary of this region. The declivity of the Zagros ranges toward the west. The mountains in this direction drop at once to the plains below, and, viewed from them, look like a huge buttress wall propping up the tableland of Persia.[1] On the south, it is supported against the coast of the Arabian Sea by the Mushti range of Balochistan, on the one hand, and upon the littoral of the Persian Gulf by the chain of mountains connecting the Balochistan range with that of Zagros, on the other. To the east these mountains support the interior tableland of Afghanistan, against the low rugged hills of the sea-coast, by the hills and valleys of Makrán; and to the west, by the hills of Laristan and Fars, they unite with the Zagros range, and support the elevated interior of Persia against the low-lying shore of the Persian Gulf. This range is pierced by many passes up to the interior, and encloses numerous fertile and well-watered valleys. Towards the north, it is separated from the valley of the Oxus and low plains of Turkistan by the Hindu Kush range on the side of Afghanistan, and from the basin of the Caspian by the Alburz range on the side of Persia.