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 country if the Aequiculi, who even in the imperial period dwelt not in towns, but in numerous open hamlets, presents a number of ancient ring-walls, which, regarded as "deserted towns" with their solitary temples, excited the astonishment of the Roman as well as of modern archaeologists, who have fancied that they could find accommodation there, the former for their "primitive inhabitants" (-aborigines-), the latter for their Pelasgians. We shall certainly be nearer the truth in recognizing these structures not as walled towns, but as places of refuge for the inhabitants of the district, such as were doubtless found in more ancient times over all Italy, although constructed in less artistic style. It was natural that at the period when the stocks that had made the transition to urban life were surrounding their towns with stone walls, those districts whose inhabitants continued to dwell in open hamlets should replace the earthen ramparts and palisades of their strongholds with buildings of stone. When peace came to be securely established throughout the land and such fortresses were no longer needed, these places of refuge were abandoned and soon became a riddle to after generations.
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Reference address : https://www.ellopos.net/elpenor/rome/1-03-settlements-latins.asp?pg=9