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
Further Conquests of Rome in Etruria - South Etruria Roman
The Tuscans, who had taken advantage of the Celtic attack on Rome to assail Veii, had accomplished nothing, because they had appeared in insufficient force; the barbarians had scarcely departed, when the heavy arm of Latium descended on the Tuscans with undiminished weight. After the Etruscans had been repeatedly defeated, the whole of southern Etruria as far as the Ciminian hills remained in the hands of the Romans, who formed four new tribes in the territories of Veii, Capena, and Falerii (367), and secured the northern boundary by establishing the fortresses of Sutrium (371) and Nepete (381).
With rapid steps this fertile region, covered with Roman colonists, became completely Romanized. About 396 the nearest Etruscan towns, Tarquinii, Caere, and Falerii, attempted to revolt against the Roman encroachments, and the deep exasperation which these had aroused in Etruria was shown by the slaughter of the whole of the Roman prisoners taken in the first campaign, three hundred and seven in number, in the market-place of Tarquinii; but it was the exasperation of impotence. In the peace (403) Caere, which as situated nearest to the Romans suffered the heaviest retribution, was compelled to cede half its territory to Rome, and with the diminished domain which was left to it to withdraw from the Etruscan league, and to enter into the relationship of subjects to Rome which had in the meanwhile been constituted primarily for individual Latin communities.
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Reference address : https://www.ellopos.net/elpenor/rome/2-04-fall-etruscan-celts.asp?pg=27