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
Respecting the internal intercourse of the Italians with each other
our written authorities are silent; coins alone furnish some
information. We have already mentioned(28) that in Italy, with the
exception of the Greek cities and of the Etruscan Populonia, there was
no coinage during the first three centuries of Rome, and that cattle
in the first instance, and subsequently copper by weight, served as
the medium of exchange.
Within the present epoch occurred the
transition on the part of the Italians from the system of barter to
that of money; and in their money they were naturally led at first to
Greek models. The circumstances of central Italy led however to the
adoption of copper instead of silver as the metal for their coinage,
and the unit of coinage was primarily based on the previous unit of
value, the copper pound; hence they cast their coins instead of
stamping them, for no die would have sufficed for pieces so large and
heavy.