Strabo Geography 3.2.11

[11] Not far from Castlon is the mountain in which they report that the [river] Guadalquiver ¹ takes its rise. They call it silver mountain on account of the silver mines which it contains. ² Polybius asserts that both the Guadiana ³ and this river have their sources in Keltiberia, notwithstanding they are separated from each other by a distance of 900 stadia; ⁴ [this we are to attribute to] the Keltiberians having increased in power, and having consequently conferred their name on the surrounding country. It appears the ancients knew the Guadalquiver under the name of the Tartessus, and Gades ⁵ with the neighbouring islands under that of Erythia; and it is thought that we should understand in this sense the words of Stesichorus ⁶ concerning the pastoral poet Geryon, that he was born almost opposite to the renowned Erythia, in a rocky cave near to the abundant springs of the silver-bedded river Tartessus. They say that on the piece of land enclosed between the two outlets of this river there formerly stood a city named, like the river, Tartessus, and that the district was called Tartessis, which the Turduli now inhabit. Eratosthenes likewise tells us that the [country] near to Calpe ⁷ was called Tartessis, and also Erythia the Fortunate Island. This Artemidorus contradicts, and says that it is as false as his other statements, that the Sacred Promontory ⁸ is distant from Gades ⁹ five days’ sail, when in fact they are [distant from each other] not more than 1700 stadia. ¹⁰ Likewise that the tide ceased at this point, whereas it passes round the whole circuit of the habitable earth. That it is easier to pass from the northern parts of Iberia into Keltica, ¹¹ than to proceed thither by sea; with many other things which he asserted on the faith of that charlatan Pytheas.