Strabo, Geography

Be this as it may, since Dioscurias is situated in such a gulf and occupies the most easterly point of the whole sea, it is called not only the recess of the Euxine, but also the "farthermost" voyage. And the proverbial verse,“To Phasis, where for ships is the farthermost run,
”must be interpreted thus, not as though the author¹ of the iambic verse meant the river, much less the city of the same name situated on the river, but as meaning by a part of Colchis the whole of it, since from the river and the city of that name there is left a straight voyage into the recess of not less than six hundred stadia. The same Dioscurias is the beginning of the isthmus between the Caspian Sea and the Euxine, and also the common emporium of the tribes who are situated above it and in its vicinity; at any rate, seventy tribes come together in it, though others, who care nothing for the facts, actually say three hundred. All speak different languages because of the fact that, by reason of their obstinacy and ferocity, they live in scattered groups and without intercourse with one another. The greater part of them are Sarmatae, but they are all Caucasii. So much, then, for the region of Dioscurias.