Of these two parallel ranges, that formed by the projections from the Ghor mountains extends in detached ridges running mostly north and south. They enclose amongst them the valleys of Sabzwár or Isapzár, and Anartarrah, and drain to the Sistan basin by the Harutrúd or Adraskand, as it is also called. The range passes to the west of the Sistan basin, of which it forms the boundary in that direction, under the name of Koh Bandán, and ultimately joins the Sarhadd mountains. The other range, joined by the spurs from Bákharz, is an extensive and elevated mountain tract, enclosing numerous plateaux and valleys, that all drain to the Khusp river, which flows on to the salt desert. The general direction of the range is from north to south, with spurs projecting east and west. It connects through the hills of Nih and Bandán with the Sarhadd mountains. The mountain barrier thus formed by the emanations from Alburz is the natural geographical boundary between Persia and Afghanistan, north and south across the length of their conterminous frontiers. It forms a wide mountain region called Irani Khorassan, or Persian Khorassan, and abounds in populous and fertile valleys, full of fruit-gardens and running streams. Its climate is variable, and its winters severe; but on the whole it is a very salubrious region, and is everywhere easily traversed by practicable passes among the hills. Its inhabitants are a very mixed community. In the southern districts they are mostly Ilyats, from different stocks, with some Persians settled in the principal towns, and all under the rule of local chiefs of Arab descent. In the central districts,—Tún, Tabbas, and northern parts of Ghazn,—there are many Baloch and Tartar families mixed up with the general population. To the north of these, in Záwah and Bákharz, the people are mostly Karai Tartars and Hazárah Uzbaks; and in the northern districts, Nishabor, Sabzwár, Burdjnurd, Khabúshán, &c., they are entirely Kurds. From the above description it will be seen that the Hindu Kush and Alburz ranges combine to form the Khorassan mountains that separate Persia from Afghanistan; that Herat, and the country north of their point of junction, is geographically separated from both, and connected by its hydrographic system with the valley of the Oxus; that in the vicinity of Herat the continuity of the Khorassan hills is interrupted, south of Bákharz, by an arm of the salt desert of Persia; and also that, with Herat as a centre, the three divergent mountain ranges—viz., those of Alburz, Ghor, and Ghazn—separate three distinct peoples—the Persians, the Afghans, and the Turkmans, with Uzbaks and other cognate tribes.