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
Lying in the heart of the great North-African roadstead, the Gulf of
Tunis, at the very spot where that beautiful basin affords the best
anchorage for vessels of larger size, and where drinkable spring water
is got close by the shore, the place proved singularly favourable for
agriculture and commerce and for the exchange of their respective
commodities--so favourable, that not only was the Tyrian settlement
in that quarter the first of Phoenician mercantile cities, but even
in the Roman period Carthage was no sooner restored than it became the
third city in the empire, and even now, under circumstances far from
favourable and on a site far less judiciously chosen, there exists and
flourishes in that quarter a city of a hundred thousand inhabitants.
The prosperity, agricultural, mercantile, and industrial, of a city
so situated and so peopled, needs no explanation; but the question
requires an answer--in what way did this settlement come to attain
a development of political power, such as no other Phoenician
city possessed?