This northern boundary presents some special features. The two great ranges approaching from the east and west bend southwards to meet in the vicinity of Herat, whence they project across the whole country, dividing the region into the two kingdoms of Persia and Afghanistan, and separating each from the intermediate region to the north—the country of the Turkmans and the Hazara, with other cognate Uzbak tribes. Thus the Hindu Kush, west of Kabul, sends off two principal ranges separated by the Hari Rúd, or river of Herat. The southern of these ranges is called Syáh Koh, and breaks up into the mountains of Ghor, which, extending south of Herat, join the Khorassan mountains emanating from the Alburz range, and form the watershed between the hydrographic systems of Afghanistan and Turkistan. That is to say, all the streams to the north of the Syáh Koh range flow to the valley of the Oxus, or to the low swampy tracts of Marv and Tajand, between the lower course of that river and the Caspian, whilst all the streams to its south flow to the Sistan basin, the receptacle for all the drainage of Afghanistan west of Ghazni. And so from the opposite direction. The Alburz range west of Mashhad sends off a succession of lofty offshoots, snow-topped in midsummer, that traverse the northern highlands of Khorassan in a direction from north-west to south-east, and enclose between them a number of elevated plateaux, such as those of Nishabor, Sabzwár, Turshíz, and Tabbas, that all drain westwards into Persia. The principal of these offshoots is the Binaloh range of mountains. It separates the plain of Mashhad from that of Nishabor, and towards the south-east connects with the high mountains of Záwah and Bákharz, north of Herat. This range forms a watershed between the drainage converging on to the great salt desert of Persia on the one side, and that flowing to the swamps of Tajand and Marv on the other. Between Záwah and Tabbas the chain of mountains is interrupted by a narrow arm of the salt desert called Kavír, which at Yúnasi projects eastward on to the plain of Kháf and Ghorian. But it is continued onwards by spurs from Bákharz which connect with the mountains of Ghazn on the one side, and with those of Ghor on the other, a little south of Herat. Here the Ghazn valley drains into Afghanistan, and onwards south the two ranges proceed in parallel lines, a strip of desert waste intervening, till they mingle in the Sarhadd mountains, through which they connect with the great southern mountain border of this region—the border previously described as extending from the Sulemán range across Balochistan and the southern provinces of Persia to the Zagros range on the west.