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
After such occurrences the Roman influence in these countries was
practically shattered, and events pursued their course there for
the present without the help of the Romans; but it is necessary for
the right understanding of the sequel that we should not wholly omit
to notice the history of the nearer, and even of the more remote,
east.
While in Egypt, shut off as it is on all sides, the status quo
did not so easily admit of change, in Asia both to the west and
east of the Euphrates the peoples and states underwent essential
modifications during, and partly in consequence of, this temporary
suspension of the Roman superintendence.
Beyond the great desert
of Iran there had arisen not long after Alexander the Great
the kingdom of Palimbothra under Chandragupta (Sandracottus)
on the Indus, and the powerful Bactrian state on the upper Oxus,
both formed from a mixture of national elements with the most
eastern offshoots of Greek civilization.