On the conquest of Babylon by Cyrus, the commercial communication between India and Europe returned to Arabia in the south, and to the Caspian and the Euxine in the north: there seem to have been two routes by these seas, both of great antiquity. In describing one of them, the ancient writers are supposed to have confounded the river Ochus, which falls into the Caspian, with the Oxus, which falls into the lake of Aral. On this supposition, the route may be traced in the following manner: the produce and manufactuers of India were collected at Patala, a town near the mouth of the Indus; they were carried in vessels up this river as far as it was navigable, where they were landed, and conveyed by caravans to the Oxus: being again shipped, they descended this river to the point where it approached nearest to the Ochus, to which they were conveyed by caravans. By the Ochus they were conveyed to the Caspian, and across it to the mouth of the river Cyrus, which was ascended to where it approached nearest the Phasis: caravans were employed again, till the merchandize were embarked at Serapana on the Phasis, and thus brought to the Black Sea. According to Pliny, Pompey took great pains to inform himself of this route; and he ascertained, that by going up the Cyrus the goods would be brought within five day's journey of the Phasis. There seems to have been some plan formed at different times, and thought of by the Emperor Claudius, to join Asia to Europe and the Caspian Sea, by a canal from the Cimmerian Bosphorus to the Caspian Sea. The route which we have thus particularly described was sometimes deviated from by the merchants: they carried their goods up the Oxus till it fell into lake Aral; crossing this, they transported them in caravans to the Caspian, and ascending the Wolga to its nearest approach to the Tanais, they crossed to the latter by land, and descended it to the sea of Azoph. Strabo describes another route: viz. across the Caucasus, from the Caspian to the Black Sea; this writer, however, must be under some mistake, for camels, which he expressly says were employed, would be of no use in crossing the mountains; it is probable, therefore, that this land communication was round by the mouth of the Caspian,--a route which was frequented by the merchants of the middle ages.