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
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
The Parthian Empire
Of still more importance in the sequel than this insurrection of the Israelites was the contemporary movement--probably originating from the same cause--in the eastern provinces, where Antiochus Epiphanes emptied the temples of the Persian gods just as he had emptied that at Jerusalem, and doubtless accorded no better treatment there to the adherents of Ahuramazda and Mithra than here to those of Jehovah. Just as in Judaea--only with a wider range and ampler proportions-- the result was a reaction on the part of the native manners and the native religion against Hellenism and the Greek gods; the promoters of this movement were the Parthians, and out of it arose the great Parthian empire.
The "Parthwa," or Parthians, who are early met with as one of the numerous peoples merged in the great Persian empire, at first in the modern Khorasan to the south-east of the Caspian sea, appear after 500 under the Scythian, i. e. Turanian, princely race of the Arsacids as an independent state; which, however, only emerged from its obscurity about a century afterwards. The sixth Arsaces, Mithradates I (579?-618?), was the real founder of the Parthian as a great power. To him succumbed the Bactrian empire, in itself far more powerful, but already shaken to the very foundation partly by hostilities with the hordes of Scythian horsemen from Turan and with the states of the Indus, partly by internal disorders. He achieved almost equal successes in the countries to the west of the great desert.
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Reference address : https://www.ellopos.net/elpenor/rome/4-01-gracchi.asp?pg=107