It was colder, moister, and the zones of cultivation far more extensive, but it may also be that these regions were not so highly elevated; indeed, there is good reason for believing that the eternal processes of expansion and contraction of the earth's crust, never altogether quiescent, is more marked in Central Asia than elsewhere, and that the gradual elevation, which is undoubtedly in operation now, may have also affected the levels of river-beds and intervening divides, and thrown out of gear much of the original natural possibilities for irrigation. However that may be, it is fairly certain that no great amount of trade ever crossed the Pamirs. Marco Polo crossed them, passing by Tashkurghan and making his way eastwards to Cathay, and has very little to say about them except in admiration of the magnificent pasturage which is just as abundant and as nutritious now as it was in his time. Idrisi's information beyond the regions of the Central Asian Khanates and the Oxus was very vague. He says that on the borders of Waksh and of Jil are Wakhan and Sacnia, dependencies of the country of the Turks. From Wakhan to Tibet is eighteen journeys. "Wakhan possesses silver mines, and gold is taken from the rivers. Musk and slaves are also taken from this country. Sacnia town, which belongs to the Khizilji Turks, is five days from Wakhan, and its territory adjoins China." Wakhan probably included the province of the same name that now forms the extreme north-eastern extension of Afghanistan, but the Tibet, which was eighteen days' journey distant, in nowise corresponds with the modern Tibet. Assuming that it was "Little Tibet" (or Ladakh), which might perhaps correspond in the matter of distance, we should still have some difficulty in reconciling Idrisi's description of the "Ville de Tibet" with any place in Ladakh. He says "the town of Tibet is large, and the country of which it is the capital carries the name." This country belongs to the "Turks Tibetians." Its inhabitants entertain relations with Ferghana, Botm,[9] and with the subjects of the Wakhan; they travel over most of these countries, and they take from them their iron, silver, precious stones, leopard skins, and Tibetan musk. This town is built on a hill, at the foot of which runs a river which discharges into the lake Berwan, situated towards the east. It is surrounded with walls, and serves as the residence of a prince, who has many troops and much cavalry, who wear coats of mail and are armed _de pied en cap_. They make many things there, and export robes and stuff of which the tissue is thick, rough, and durable. These robes cost much, and one gets slaves and musk destined for Ferghana and India. There does not exist in the world creatures endowed with more beautiful complexions, with more charming figures, more perfect features, and more agreeable shape than these Turk slaves. They are disrobed and sold to merchants, and it is this class of girl who fetches 300 dinars.