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
Among the states of the second rank, merely an indirect importance,
so far as concerned the contact of the east with the west, attached
in the first instance to that series of states which, stretching from
the southern end of the Caspian Sea to the Hellespont, occupied the
interior and the north coast of Asia Minor: Atropatene (in the modern
Aderbijan, south-west of the Caspian), next to it Armenia, Cappadocia
in the interior of Asia Minor, Pontus on the south-east, and Bithynia
on the south-west, shore of the Black Sea.
All of these were
fragments of the great Persian Empire, and were ruled by Oriental,
mostly old Persian, dynasties--the remote mountain-land of Atropatene
in particular was the true asylum of the ancient Persian system, over
which even the expedition of Alexander had swept without leaving a
trace--and all were in the same relation of temporary and superficial
dependence on the Greek dynasty, which had taken or wished to take
the place of the great-kings in Asia.