This route from India to the West by the Oxus and the Caspian, sometimes called the northern route, is supposed to be given twice by Strabo and once by Pliny; there is nothing else, for Solinus 19,4 is merely copied from Pliny. The correct explanation was given by Professor Kiessling in 1914, but it was given in a couple of sentences in the middle of a very long article on Hyrcania and has never been taken up or followed; and the whole subject has been such a mass of misunderstanding that it is worth setting out the formal proofs.

Strabo ii, 73. A comparison with xi, 509 shows both that this is from Patrocles and that it is not Eratosthenes' version of Patrocles; it may therefore be taken to be what Patrocles said himself. The literal translation is: ‘The Oxus is sufficiently navigable for the Indian trade to be carried across to it and to be easily brought down the river to the Hyrcanian (sea) and the places beyond as far as the Black Sea by way of the rivers’, i.e. the Cyrus and the Phasis. This sober statement is part of Patrocles' report to Antiochus I, and in Greek, as in English, it can mean two things: (1) that the Indian trade was being brought down the Oxus to the Caspian and beyond, and (2) that it was not being so brought but easily could be. The word ‘easily’ shows that (2) is the real meaning of Patrocles' report; he told Antiochus that it would be easy to make a trade route.