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
Far more important in an historical point of view was the great settlement of the Tuscans in the land which still bears their name. Although Ligurians or Umbrians were probably at one time(5) settled there, the traces of them have been almost wholly effaced by the Etruscan occupation and civilization. In this region, which extends along the coast from Pisae to Tarquinii and is shut in on the east by the Apennines, the Etruscan nationality found its permanent abode and maintained itself with great tenacity down to the time of the empire.
5. Cf. I. VIII. Umbro-Sabellian Migration
The northern boundary of the proper Tuscan territory was formed by the Arnus; the region north from the Arnus as far as the mouth of the Macra and the Apennines was a debateable border land in the possession sometimes of Ligurians, sometimes of Etruscans, and for this reason larger settlements were not successful there. The southern boundary was probably formed at first by the Ciminian Forest, a chain of hills south of Viterbo, and at a later period by the Tiber.
We have already(6) noticed the fact that the territory between the Ciminian range and the Tiber with the towns of Sutrium, Nepete, Falerii, Veii, and Caere appears not to have been taken possession of by the Etruscans till a period considerably later than the more northern districts, possibly not earlier than in the second century of Rome, and that the original Italian population must have maintained its ground in this region, especially in Falerii, although in a relation of dependence.
6. Cf. I. VIII. Their Political Development
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/1-09-etruscans.asp?pg=9