Afghanistan is a continental state of SW Asia. It borders with Turkmenistan, Uzbekistan, and Tajikistan to the N, with China for a short distance to the NE (the appendix wedged between the Pamir and the Hindukush), with Pakistan to the E and S, with l ‘ Iran to O.
The exploration of the to. it began with the various expeditions made by Alexander the Macedonian (330-327 BC). Other crossings of the country took place in the century. 14 ° by Ibn Baṭṭūṭa, and in 1602-03 thanks to his father B. de Goes. Important reconnaissance was carried out at the beginning of the century. 19 °, but the first real scientific exploration was that (1826-38) of the American C. Masson, followed by the travels of JS Broadfoot (1839), of JP Ferrier (1845-54), of Major Lumsden (1857-1858); the war of 1878 and the military operations of 1881 in Wāzīrīstān gave rise to extensive topographical and cartographic works, which were followed by systematic topographical surveys as part of the survey, for political purposes, of the whole region of Asia (1884-86, 1894- 96); between 1914 and 1916 a German mission was carried out. With the recognition of political independence (1919) the Afghanistan established direct relations with various states and thus began the detailed exploration (especially for the NW and NE regions).
The Afghan territory, which constitutes the north-eastern portion of the Iranian plateau, has a distinctly mountainous character: in fact, over 49% of the territory exceeds 2000 m and the average height of Hindukush is 4500 m. In this exasperated plastic physiognomy, three morphological zones can be identified: a central one of real mountains, of Alpine age, dividing bastion between the other two less elevated ones, located to the N and to S. Dall’Hari, to the West, extends towards the E first the Paropamiso chain(2000 m high on average; max 3594 m), flanked by other chains which, rising over 3000 m, narrow at the imposing Kūh-i Bābā massif (5143 m), well watered (as shown by the thick mantle snowy on the top), in turn accompanied to the North by a large band of ‘ pre-Alps ‘. To the East the relief widens again in the Hindukush proper, a set of parallel chains with a prevalence of granite and metamorphic rocks, whose culminating parts take on worn horizontal shapes, in evident contrast with the marked steepness of the gorges that cross it.. At the eastern end the mountains, as they lower, curve little by little towards the Pamir: the valleys that interpose themselves remain at a considerable altitude, so that the difference in height is modest compared to the peaks themselves.
According to directoryaah, the northern area of the Afghanistan, the ancient Bactrian, is made up of a foothill belt, slowly sloping down into a plateau of Mesozoic limestone, the limits of which drop sheer to the Amudar´ja plain, towards which the courses flow of water: this is formed by extensive alluvial and aeolian layers, inclined towards the great river, with areas often covered by mobile dunes, witnesses of a desert environment; however, in the valleys and in the direction of the foothills it becomes fertile, with agricultural oases, which transform it into one of the most productive regions of the country.
The third morphological zone is identified with the southern part of the Afghanistan: it is first a jumble of chains that from the Hindukush system, with NE-SW orientation, come to die in the vast tabular and desert area divided into two sections by the Helmand River. This, flowing in, after having collected the waters of the immense mountain amphitheater, flows into the bodies of water of Hāmūn-i-Sabari and Gaud-i-Zirih, which occupy the sinking basin of the Sistan.
Geographical position, altimetry and relief arrangement play a decisive role on the climate of Afghanistan, which has continental characteristics almost everywhere. Precipitation is concentrated in the winter and spring periods and is generally scarce: from 50-150 mm in the lowlands, including the southern and northern sub-desert and desert areas, it passes to values even higher than 500 mm per year in the north-eastern reliefs (Nūristān), marginally influenced by the sea monsoon. A subtropical, temperate climate, which allows Mediterranean crops, affects the southern and eastern portions of the country. Among the winds we must remember that of the ‘120 days’, which blows constantly and with particular violence in Sistan and Khorasan from June to September.
As a consequence of its morphological structure, a large part of the Afghan territory is devoid of drainage to the sea: this is true for the rivers that from the opposite sides of the central highlands pay N and S, respectively to the Amudar´ja (and therefore to Lake d ‘Aral) and the endorheic depressions of the Sistan, or are consumed in the steppe areas they cross. An exception is a small area of NE which, via Kabul and a few other rivers, sends its waters to the Indus.From the Kūh-i Bābā, the main hydrographic node of the Afghanistan, other major arteries radiate: such as the Surkhāb, the Hari, the Helmand with the Arghand-āb and the mentioned Kabul. The flow rates are conditioned by the climate: those fed by the melting of snow and glaciers are less irregular, while the others are decidedly torrential. The dune desert of Rigestan represents an extensive areic area.