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
Let us first glance at the Roman dramatic literature and the stage
itself. Tragedy has now for the first time her specialists; the
tragic poets of this epoch do not, like those of the preceding,
cultivate comedy and epos side by side. The appreciation of this
branch of art among the writing and reading circles was evidently
on the increase, but tragic poetry itself hardly improved. We now
meet with the national tragedy (-praetexta-), the creation of
Naevius, only in the hands of Pacuvius to be mentioned immediately--
an after-growth of the Ennian epoch. Among the probably numerous
poets who imitated Greek tragedies two alone acquired a
considerable name.
Marcus Pacuvius from Brundisium (535-c. 625)
who in his earlier years earned his livelihood in Rome by painting
and only composed tragedies when advanced in life, belongs as
respects both his years and his style to the sixth rather than
the seventh century, although his poetical activity falls within
the latter. He composed on the whole after the manner of his
countryman, uncle, and master Ennius.