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
The plain of Latium must have been in primeval times the scene of the grandest conflicts of nature, while the slowly formative agency of water deposited, and the eruptions of mighty volcanoes upheaved, the successive strata of that soil on which was to be decided the question to what people the sovereignty of the world should belong. Latium is bounded on the east by the mountains of the Sabines and Aequi which form part of the Apennines; and on the south by the Volscian range rising to the height of 4000 feet, which is separated from the main chain of the Apennines by the ancient territory of the Hernici, the tableland of the Sacco (Trerus, a tributary of the Liris), and stretching in a westerly direction terminates in the promontory of Terracina. On the west its boundary is the sea, which on this part of the coast forms but few and indifferent harbours. On the north it imperceptibly merges into the broad hill-land of Etruria.
The region thus enclosed forms a magnificent plain traversed by the Tiber, the "mountain-stream" which issues from the Umbrian, and by the Anio, which rises in the Sabine mountains. Hills here and there emerge, like islands, from the plain; some of them steep limestone cliffs, such as that of Soracte in the north-east, and that of the Circeian promontory on the south-west, as well as the similar though lower height of the Janiculum near Rome; others volcanic elevations, whose extinct craters had become converted into lakes which in some cases still exist; the most important of these is the Alban range, which, free on every side, stands forth from the plain between the Volscian chain and the river Tiber.
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Reference address : https://www.ellopos.net/elpenor/rome/1-03-settlements-latins.asp?pg=4