Strabo, Geography

Aristobulus¹ calls the river which flows through Sogdiana Polytimetus, a name imposed by the Macedonians (just as they imposed names on many other places, giving new names to some and slightly altering the spelling of the names of others); and watering the country it empties into a desert and sandy land, and is absorbed in the sand, like the Arius which flows through the country of the Arians. It is said that people digging near the Ochus River found oil. It is reasonable to suppose that, just as nitrous² and astringent and bituminous and sulphurous liquids flow through the earth, so also oily liquids are found; but the rarity causes surprise.³ According to some, the Ochus flows through Bactriana; according to others, alongside it. And according to some, it is a different river from the Oxus as far as its mouths, being more to the south than the Oxus, although they both have their outlets into the Caspian Sea in Hyrcania, whereas others say that it is different at first, but unites with the Oxus, being in many places as much as six or seven stadia wide. The Iaxartes, however, from beginning to end, is a different river from the Oxus, and although it ends in the same sea, the mouths of the two, according to Patrocles, are about eighty parasangs distant from one another. The Persian parasang, according to some, is sixty stadia, but according to others thirty or forty. When I was sailing up the Nile, they used different measures when they named the distance in "schoeni" from city to city, so that in some places the same number of "schoeni" meant a longer voyage and in others a shorter;⁴ and thus the variations have been preserved to this day as handed down from the beginning.