Where a mountain system describes a semi-circular course, its transit routes tend to converge on the inner side, and at their foci fix the sites of busy commercial centers.  Turin draws on a long series of Alpine and Apennine routes from the Pass of Giovi (1548 feet or 472 meters) leading up from Genoa on the south, to the Great St. Bernard on the north.  Milan gets immense support from the St. Gotthard and Simplon railroads over the Alps, besides wagon routes over several minor passes.  Kulm, Balkh and Kunduz in the piedmont of northern Afghanistan are fed by twenty or more passes over the Hindu Kush and Pamir.  Bukhara is the remoter focus of all these routes, and also of the valley highways of the western Tian Shan.  It therefore occupies a location which would make it one of the great emporiums of the world, were it not for the expanse of desert to the west and the scantiness of its local water supply, which is tapped farther upstream for the irrigation of Samarkand.  In its bazaars are found drugs, dyes and teas from India; wool, skins and dried fruit from Afghanistan; woven goods, arms, and books from Persia; and Russian wares imported by rail and caravan.  English goods, which formerly came in by the Kabul route from India, have been excluded since Russia established a protectorate over the province of Bukhara.  Across the highlands to the east, the cities of Kashgar and Yarkand, situated in that piedmont zone of vegetation where mountain and desert meet, are enclosed by a vast amphitheater formed by the Tian Shan, the Pamir Highlands, and the Karakorum range.  Stieler’s atlas marks no less than six trade routes over the passes of these mountains from Kashgar to the headstreams of the Sir-daria and Oxus, and six from Yarkand to the Oxus and Indus.  Kashgar is a meeting ground of many nationalities.  To its bazaars come traders from China, India, Afghanistan, Bukhara, and Russian Turkestan.[1199] The Russian railway up the Sir-daria to Andizhan brings European goods within relatively easy reach of the Terek Davan Pass, and makes serious competition for English wares entering by the more difficult Karakorum Pass from India.[1200]

[Sidenote:  Cities of coastal piedmonts.]

Where mountains drop off into a desert, as these Central Asiatic ranges do, their piedmont cities are confined to a narrow zone between mountains and arid waste.  Bordering two transit regions of scant population and through travel, they become natural outfitting points, centers of exchange rather than production.  Where mountains drop off into the sea and the piedmont therefore becomes a coastal belt, again it borders two transit regions; but here the ports of the desert are replaced by maritime ports, which command the world thoroughfare of the ocean.  They therefore tend to concentrate population and commerce wherever a good harbor coincides with the outlet of a transmontane route, as in Genoa and Bombay.

[Sidenote:  Piedmonts as colonial or backwoods frontiers.]