Before the Christian era several trade-routes between Europe and the Orient lay across this region, and along the caravan routes there were the usual industries pertaining to commercial peoples. The cities of Sinope, Trebizond, Astrabad, Phasis, Mashad, and Bactra (now Balkh) grew into existence along one of the northern routes. Tyre, Nineveh, Tarsus, Palmyra, Babylon, and Persepolis were founded along one or another of the southern routes. Of these, Trebizond only retains its importance, being a seaport with a considerable trade. The commerce that once passed over this route was crushed out of existence during the invasions by Jenghis Khan. [Illustration: A KABISTAN RUG--CAUCASUS DISTRICT] Of the various industries of the Iran plateau, practically but one extends beyond its borders, namely, the manufacture of the textile fabrics known as Oriental rugs. These are unique; they are made of materials, colored with dyes, and are ornamented with designs that cannot be successfully imitated anywhere else in the world. The filling of the rugs consists of fine wool, selected not only from particular localities, but also from certain parts of the fleece. The dye-stuffs are common to other parts of the world, and their names--indigo, saffron, coccus, madder, and orchil--are familiar. But both the wool and the dye-stuffs possess qualities imparted to them by soil and climate that are not found elsewhere. The absence of floors, and of the furniture found in European dwellings, make the rugs essential household articles rather than luxuries. The hearth-rug, the bath-mat, the divan-cover, the sleeping-blanket, and the saddle-mat must be regarded as necessities. Religion also has its requirements, and the prayer rug, sometimes ornamented with the hands of the Prophet, is a part of every household equipment, whether of the nomadic Arab or the wealthy merchant. Each district and people have their own designs and methods of workmanship, and the rugs of each are easily distinguished.[76] For the greater part these are gathered by caravans and conveyed to convenient shipping-points. Nearly all the cottage-made product is obtained in this manner. As a rule the rugs are named from the town or district in which they are made. Smyrna and Constantinople are the chief ports of shipment. Many of them find their way to European dealers, but New York is probably the largest rug-market in the world. The great majority are retailed at from ten to fifty dollars each; choice fabrics, however, bring from three hundred to ten thousand dollars. Oriental rugs are hand-woven, and a weaver frequently spends several years on a single piece, earning perhaps less than ten cents a day. The factory-made rugs are inferior to the cottage-manufactured product.