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
In the seventh century this absolute centralization of the public
life of the Roman community in the one focus of Rome was given up,
so far as Italy at least was concerned. Now that Italy was a
single civic community and the civic territory reached from the Arnus
and Rubico down to the Sicilian Straits,(41) it was necessary to
consent to the formation of smaller civic communities within that
larger unit.
So Italy was organized into communities of full
burgesses; on which occasion also the larger cantons that were
dangerous from their size were probably broken up, so far as this
had not been done already, into several smaller town-districts.(42)
