The successor of Volagases I. was Pacorus, whom most writers on Parthian history have regarded as his son. There is, however, no evidence of this relationship; and the chief reason for regarding Pacorus as belonging even to the same branch of the Arsacidse with Volagases I. is his youth at his accession, indicated by the beardless head upon his early coins, which is no doubt in favor of his having been a near relation of the preceding king.
The Parthian coins show that his reign continued at least till A.D. 93; it may have lasted considerably longer, for the earliest date on any coin of Chosroes is AEr. Seleuc. 421, or A.D. 110. The accession of Chosroes has been conjecturally assigned to A.D. 108, which would allow to Pacorus the long reign of thirty years. Of this interval it can only be said that, so far as our knowledge goes, it was almost wholly uneventful. We know absolutely nothing of this Pacorus except that he gave encouragement to a person who pretended to be Nero; that he enlarged and beautified Otesiphon; that he held friendly communications with Decebalus, the great Dacian chief, who was successively the adversary of Domitian and Trajan; and that he sold the sovereignty of Osrhoene at a high price to the Edessene prince who was cotemporary with him. The Pseudo-Nero in question appears to have taken refuge with the Parthians in the year A.D. 89, and to have been demanded as an impostor by Domitian. Pacorus was at first inclined to protect and to even assist him, but after a while was induced to give him up, probably by a threat of hostilities. The communication with the Dacian chief was most likely earlier.
The Dacians, in one of those incursions into Maesia which they made during the first years of Domitian, took captive a certain Callidromus, a Greek, if we may judge by his name, slave to a Roman of some rank, named Liberius Maximus. This prisoner Decebalus (we are told) sent as a present to Pacorus, in whose service and favor he remained for a number of years. This circumstance, insignificant enough in itself, acquires an interest from the indication which it gives of intercommunication between the enemies of Rome, even when they were separated by vast spaces, and might have been thought to have been wholly ignorant of each other's existence. Decebalus can scarcely have been drawn to Pacorus by any other attraction than that which always subsists between enemies of any great dominant power. He must have looked to the Parthian monarch as a friend who might make a diversion on his behalf upon occasion; and that monarch, by accepting his gift, must be considered to have shown a willingness to accept this kind of relation.
The sale of the Osrhoene territory to Abgarus by Pacorus was not a fact of much consequence. It may indicate an exhaustion of his treasury, resulting from the expenditure of vast sums on the enlargement and adornment of the capital, but otherwise it has no bearing on the general condition of the Empire. Perhaps the Parthian feudatories generally paid a price for their investiture. If they did not, and the case of Abgarus was peculiar, still it does not appear that his purchase at all altered his position as a Parthian subject. It was not until they transferred their allegiance to Rome that the Osrhoene princes struck coins, or otherwise assumed the status of kings. Up to the time of M. Aurelius they continued just as much subject to Parthia as before, and were far from acquiring a position of independence.
There is reason to believe that the reign of Pacorus was a good deal disturbed by internal contentions. We hear of an Artabanus as king of Parthia in A.D. 79; and the Parthian coins of about this period present us with two very marked types of head, both of them quite unlike that of Pacorus, which must be those of monarchs who either contended with Pacorus for the crown, or ruled contemporaneously with him over other portions of the Parthian Empire. Again, towards the close of Pacorus's reign, and early in that of his recognized successor, Chosroes, a monarch called Mithridates is shown by the coins to have borne sway for at least six years—from A.D. 107 to 113.
This monarch commenced the practice of placing a Semitic legend upon his coins, which would seem to imply that he ruled in the western rather than the eastern provinces. The probability appears, on the whole, to be that the disintegration which has been already noticed as having commenced under Volagases I. was upon the increase. Three or four monarchs were ruling together in different portions of the Parthian world, each claiming to be the true Arsaces, and using the full titles of Parthian sovereignty upon his coins. The Romans knew but little of these divisions and contentions, their dealings being only with the Arsacid who reigned at Ctesiphon and bore sway over Mesopotamia and Adiabene.
Pacorus must have died about A.D. 108, or a little later. He left behind him two sons, Exedares and Parthamasiris, but neither of these two princes was allowed to succeed him. The Parthian Megistanes assigned the crown to Chosroes, the brother of their late monarch, perhaps regarding Exedares and Parthamasiris as too young to administer the government of Parthia satisfactorily. If they knew, as perhaps they did, that the long period of peace with Rome was coming to an end, and that they might expect shortly to be once more attacked by their old enemy, they might well desire to have upon the throne a prince of ripe years and approved judgment. A raw youth would certainly have been unfit to cope with the age, the experience, and the military genius of Trajan.