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.

As the Euxine Sea was the grand point to which all these routes tended, the towns on it became the resort of an immense number of merchants, even at very early ages; and the kingdoms of Prusias, Attalus, and Mithridates were enriched by their commerce.  Herodotus mentions, that the trade of the Euxine was conducted by interpreters of seven different languages.  In the time of Mithridates, 300 different nations, or tribes, met for commercial purposes at Dioscurias in Colchis; and soon after the Romans conquered the countries lying on the Euxine, there were 130 interpreters of languages employed in this and the other trading towns.  The Romans, however, as soon as they became jealous, or afraid, of the power of the Parthians, would not suffer them, or any other of the northern nations, to traffic by the Euxine; but endeavoured, as far as they could, to confine the commerce of the East to Alexandria:  the consequence was, that even so early as the age of Pliny, Dioscurias was deserted.

The only article of import into Rome that remains to be considered is silk:  the history of the knowledge and importation of this article among the ancients, and the route by which it was obtained, will comprise all that it will be necessary to say on this subject.

The knowledge of silk was first brought into Europe through the conquests of Alexander the Great.  Strabo quotes a passage from Nearchus, in which it is mentioned, but apparently confounded, with cotton.  It is well known that Aristotle obtained a full and accurate account of all the discoveries in natural history which were made during the conquests of Alexander, and he gives a particular description of the silk worm; so particular, indeed, that it is surprising how the ancients could, for nearly 600 years after his death, be ignorant of the nature and origin of silk.  He describes the silk worm as a horned worm, which he calls bombyx, which passes through several transformations, and produces bombytria.  It does not appear, however, that he was acquainted either with the native country of this [work->worm], or with such a people as the Seres; and this is the only reason for believing that he may allude entirely