Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Those who did so were chiefly the Boii, who are alleged to have penetrated into Italy by another route, over the Poenine Alps (the Great St. Bernard): they settled in the modern Romagna, where the old Etruscan town Felsina, with its name changed by its new masters to Bononia, became their capital. Finally came the Senones, the last of the larger Celtic tribes which made their way over the Alps; they took up their abode along the coast of the Adriatic from Rimini to Ancona.
But isolated bands of Celtic settlers must have advanced even far in the direction of Umbria, and up to the border of Etruria proper; for stone-inscriptions in the Celtic language have been found even at Todi on the upper Tiber. The limits of Etruria on the north and east became more and more contracted, and about the middle of the fourth century the Tuscan nation found themselves substantially restricted to the territory which thenceforth bore and still bears their name.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/2-04-fall-etruscan-celts.asp?pg=16