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
Oldest Settlements in the Palatine and Suburan Regions
The Palatine was the original seat of the Roman community, the oldest and originally the only ring-wall. The urban settlement, however, began at Rome as well as elsewhere not within, but under the protection of, the stronghold; and the oldest settlements with which we are acquainted, and which afterwards formed the first and second regions in the Servian division of the city, lay in a circle round the Palatine. These included the settlement on the declivity of the Cermalus with the "street of the Tuscans"--a name in which there may have been preserved a reminiscence of the commercial intercourse between the Caerites and Romans already perhaps carried on with vigour in the Palatine city--and the settlement on the Velia; both of which subsequently along with the stronghold-hill itself constituted one region in the Servian city.
Further, there were the component elements of the subsequent second region--the suburb on the Caelian, which probably embraced only its extreme point above the Colosseum; that on the Carinae, the spur which projects from the Esquiline towards the Palatine; and, lastly, the valley and outwork of the Subura, from which the whole region received its name. These two regions jointly constituted the incipient city; and the Suburan district of it, which extended at the base of the stronghold, nearly from the Arch of Constantine to S. Pietro in Vincoli, and over the valley beneath, appears to have been more considerable and perhaps older than the settlements incorporated by the Servian arrangement in the Palatine district, because in the order of the regions the former takes precedence of the latter.
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Reference address : https://www.ellopos.net/elpenor/rome/1-04-beginnings-rome.asp?pg=12