Titus Livius (Livy), The History of Rome, Book 5
Rev. Canon Roberts, Ed.

35. Subsequently another body, consisting of the Cenomani, under the leadership of Elitovius, followed the track of the former and crossed the Alps by the same pass, with the goodwill of Bellovesus. They had their settlements where the cities of Brixia and Verona now stand. [2] The Libui came next and the Saluvii; they settled near the ancient tribe of the Ligurian Laevi, who lived about the Ticinus. Then the Boii and Lingones crossed the Pennine Alps, and as all the country between the Po and the Alps was occupied, they crossed the Po on rafts and expelled not only the Etruscans but the Umbrians as well. [3] They remained, however, north of the Apennines. Then the Senones, the last to come, occupied the country from the Utis to the Aesis. It was this last tribe, I find, that came to Clusium, and from there to Rome; [4] but it is uncertain whether they came alone or helped by contingents from all the Cisalpine peoples.

The¹ people of Clusium were appalled by this strange war, when they saw the numbers, the extraordinary appearance of the men, and the kind of weapons they used, and heard that the legions of Etruria had been often routed by them on both sides of the Po. Although they had no claim on Rome, either on the ground of alliance or friendly relations, unless it was that they had not defended their kinsmen at Veii against the Romans, they nevertheless sent ambassadors to ask the senate for assistance. [5] Active assistance they did not obtain. The three sons of M. Fabius Ambustus were sent as ambassadors to negotiate with the Gauls and warn them not to attack those from whom they had suffered no injury, who were allies and friends of Rome, and who, if circumstances compelled them, must be defended by the armed force of Rome. [6] They preferred that actual war should be avoided, and that they should make acquaintance with the Gauls, who were strangers to them, in peace rather than in arms.