Strabo Geography 3.3.4

[4] The country which we are describing is fertile, and irrigated by rivers both large and small, all of which flow from the eastern parts parallel with the Tagus: most of them are navigable and full of gold dust. After the Tagus, the most noted rivers are the Mondego ¹ and the Vouga, ² which are navigable but for a short distance. After these is the Douro, ³ which flows from afar by Numantia, ⁴ and many other colonies of the Keltiberians and Vaccaei; it is capable of being navigated in large vessels for a distance of nearly 800 stadia. Besides these there are other rivers, after which is the [river] of Lethe, which some call the Limaea, ⁵ others the Belio, ⁶ it likewise rises amongst the Keltiberians and Vaccaei. After this is the Baenis, (some call it the Minius, ⁷ ) by far the largest river of Lusitania, ⁸ being navigable for a distance of 800 stadia. Posidonius says this too rises amongst the Cantabrians. ⁹ An island ¹⁰ lies before its outlet, and two moles affording anchorage for vessels. A natural advantage [of this country] well deserving of commendation is, that the banks of the rivers are so lofty as to be capable of containing the entire of the water raised by the high tides of the sea, without either being overfilled, or overflowing the plains. This was the limit of Brutus’s expedition. Beyond there are many other rivers parallel to those I have named.