Varro, de Lingua Latina 5.4:
“There are various accounts of how the Tiber got its name. For both Etruria and Latium thought that the Tiber was their own, because there were those who said that it was first named the Thebris after Thebris, a neighboring prince of Veii. There are also those who committed to writing the claim that the early Latin name of the river was Albula, but it was renamed after Tiberinus ruled as king of the Latins because he died in it – the Tiber is, as they tell it, his grave.”
Sed de Tiberis nomine anceps historia. Nam et suum Etruria et Latium suum esse credit, quod fuerunt qui ab Thebri vicino regulo Veientum, dixerint appellatum, primo Thebrim. Sunt qui Tiberim priscum nomen Latinum Albulam vocitatum litteris tradiderint, posterius propter Tiberinum regem Latinorum mutatum, quod ibi interierit: nam hoc eius ut tradunt sepulcrum.