Titus Livius (Livy), The History of Rome, Book 5
D. Spillan, A.M., M.D., Ed.

33. That citizen being driven away, who being present, Rome could not be captured, if any thing is certain regarding human affairs; the destined ruin now approaching the city, ambassadors came from the Clusinians, soliciting aid against the Gauls. [2] A report is current that that nation, allured by the delightfulness of the crops, and more especially of the wine, an enjoyment then new to them, crossed the Alps, and took possession of the lands formerly cultivated by the Etrurians; [3] and that Aruns, a native of Clusium, introduced wine into Gaul for the purpose of enticing the nation, through resentment for his wife's having been debauched by Lucumo, whose guardian he himself had been, a very influential young man, and on whom vengeance could not be taken, unless foreign aid were resorted to; [4] that this person served as a guide to them when crossing the Alps, and advised them to lay siege to Clusium. [5] I would not indeed deny that the Gauls were brought to Clusium by Aruns or any other native of Clusium; but that those persons who laid siege to Clusium were not they who first crossed the Alps, is sufficiently certain. For two hundred years before they laid siege to Clusium and captured the city of Rome, the Gauls passed over into Italy. [6] Nor were these the first of the Etrurians with whom the Gauls fought, but long before that they frequently fought with those who dwelt between the Apennines and the Alps. [7] Before the Roman empire the sway of the Tuscans was much extended by land and by sea; how very powerful [p. 365]they were in the upper and lower seas, by which Italy is encompassed like an island, the names [of these seas] is a proof; [8] the one of which the Italian nations have called the Tuscan sea, the general appellation of the people; the other the Hadriatic, from Hadria, a colony of Tuscans. [9] The Greeks call these same seas the Tyrrhenian and Hadriatic. This people inhabited the country extending to both seas in twelve cities, colonies equal in number to the mother cities having been sent, first on this side the Apennines towards the lower sea, afterwards to the other side of the Apennines; [10] who obtained possession of all the district beyond the Po, even as far as the Alps, except the corner of the Venetians, who dwell round the extreme point of the [Hadriatic] sea. [11] The Alpine nations also have this origin, more especially the Rhaetians; whom their very situation has rendered savage, so as to retain nothing of their original, except the accent of their language, and not even that without corruption.