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
Home of the Etruscans
It is equally difficult to determine from what quarter the Etruscans migrated into Italy; nor is much lost through our inability to answer the question, for this migration belonged at any rate to the infancy of the people, and their historical development began and ended in Italy. No question, however, has been handled with greater zeal than this, in accordance with the principle which induces antiquaries especially to inquire into what is neither capable of being known nor worth the knowing--to inquire "who was Hecuba's mother," as the emperor Tiberius professed to do.
As the oldest and most important Etruscan towns lay far inland--in fact we find not a single Etruscan town of any note immediately on the coast except Populonia, which we know for certain was not one of the old twelve cities-- and the movement of the Etruscans in historical times was from north to south, it seems probable that they migrated into the peninsula by land. Indeed the low stage of civilization, in which we find them at first, would ill accord with the hypothesis of immigration by sea.
Nations even in the earliest times crossed a strait as they would a stream; but to land on the west coast of Italy was a very different matter. We must therefore seek for the earlier home of the Etruscans to the west or north of Italy. It is not wholly improbable that the Etruscans may have come into Italy over the Raetian Alps; for the oldest traceable settlers in the Grisons and Tyrol, the Raeti, spoke Etruscan down to historical times, and their name sounds similar to that of the Ras. These may no doubt have been a remnant of the Etruscan settlements on the Po; but it is at least quite as likely that they may have been a portion of the people which remained behind in its earlier abode.
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Reference address : https://www.ellopos.net/elpenor/rome/1-09-etruscans.asp?pg=6