It appears, however, from the account of Justin, and from such other notices as have reached us of the condition of things at this time in the regions lying east of the Caspian, that Mithridates was entirely successful where his father and his cousin had signally failed.  He gained a number of victories over the Scythic hordes; and effectually checked their direct progress towards the south, throwing them thereby upon the east and the south-east.  Danger to Parthia from the Scyths seems after his reign to have passed away.  They found a vent for their superabundant population in Seistan, Afghanistan, and India, and ceased to have any hopes of making an impression on the Arsacid kingdom.  Mithridates, it is probable, even took territory from them.  The acquisition of parts of Bactria by the Parthians from the Scyths, which is attested by Strabo, belongs, in all likelihood, to his reign; and the extension of the Parthian dominion to Seistan may well date from the same period.  Justin tells us that he added many nations to the Parthian Empire.  The statements made of the extent of Parthia on the side of Syria in the time of Mithridates the First render it impossible for us to discover these nations in the west:  we are, therefore, compelled to regard them as consisting of races on the eastern frontier, who could at this period only be outlying tribes of the recent Scythic immigration.

The victories of Mithridates in the East encouraged him to turn his arms in the opposite direction, and to make an attack on the important country of Armenia, which bordered his north-western frontier.  Armenia was at the time under the government of a certain Ortoadistus, who seems to have been the predecessor, and was perhaps the father, of the great Tigranes.  Ortoadistus ruled the tract called by the Romans “Armenia Magna,” which extended from the Euphrates on the west to the mouth of the Araxes on the east, and from the valley of the Kur northwards to Mount Niphates and the head streams of the Tigris towards the south.  The people over which he ruled was one of the oldest in Asia and had on many occasions shown itself impatient of a conqueror.  Justin, on reaching this point in his work, observes that he could not feel himself justified if, when his subject brought before him so mighty a kingdom, he did not enter at some length on its previous history.  The modern historian would be even less excusable than Justin if he omitted such a review, since, while he has less right to assume a knowledge of early Armenian history on the part of his readers, he has greater means of gratifying their curiosity, owing to the recent discovery of sources of information unknown to the ancients.