From these sources we obtain a very fair idea of the general conformation of Central Afghanistan, _i.e._ that part of Afghanistan which is occupied by the tribes known as the Chahar Aimak, _i.e._ the Jamshidis, the Hazaras, Firozkohis, and Taimanis. It consists in the first place of a huge irregular tableland--or uplift--which has been deeply scored and eroded by centuries of river action, the rivers radiating from the central mass of the Koh-i-Babar to the west of Kabul and flowing in deep valleys either directly northward towards the Oxus, due west towards Herat (eventually to turn northward), or south-west in irregular but more or less parallel lines to the Helmund lagoons in Seistan. The Kabul River basin also finds its head near the same group of river sources. The central mountain mass, the Koh-i-Babar, is high, rocky, generally snow-capped and impassable. To the north it sends down long, barren, and comparatively gentle spurs to the main plateau level, which is deeply cut into by the northern system of rivers, including the Murghab and the Balkh Ab. But the strangest feature in this network of hydrography is the long, deep, narrow valley (almost ditch-like in its regularity) which has been eroded by the Hari Rud River as it makes its way due west, cutting off the sources of the northern group from those of the Helmund or south-western group. It is a most remarkable valley, depressed to a depth of 1000 to 2000 feet below the general plateau level, bounded on the north by a comparatively level line of red-faced cliffs, and on the south by another straight flat-backed range called the Band-i-Baian (or farther west, the Sufed Koh), which has been carved into the semblance of a range by the parallel valleys of the Hari Rud on the north and the Tagao Ishlan on the south, which hug the range between them.