Each of the succeeding Arsacid rulers was known during his lifetime by the throne-name Arsaces, a custom which does nothing to facilitate the work of the historian or numismatist. None the less the Arsacid date, anno 157, included in the text fixes it to the year 91 B.C., and thus suggests that the ruler under whom it was written would have been either Mithradates II (c. 123-88/7 B.C.) or Gotarzes I (91-81/80 B.C.) whose reigns overlapped at this time during several years. Mithradates II was indeed, and Gotarzes I may well have been, grandsons of Priapatius, and the latter in turn a nephew's son of the first Arsaces. The historicity of the first Arsaces, and the general correctness of the succession, as transmitted by the classical historians, is thus confirmed. The genealogical table compiled by Frye is based on these assumptions,1 but those offered by Chaumont and Bickerman depend on somewhat varied interpretations, and must be subject to reservations. There seems at any rate sufficient justification for accepting the traditional version of events: that Arsaces, chief of the Parni, and perhaps originally a local ruler in Bactria, crushed Andragoras, veteran satrap of Parthia and Hyrcania in about 238 B.C. and mastered those provinces. He repelled the punitive expedition of Seleucus II, and was succeeded by his able brother Tiridates. The latter in turn was succeeded by his son Artabanus I, who opposed the invasion of Antiochus III in 209 B.C. Artabanus again was succeeded by his son Priapatius, who reigned for fifteen years to 176 B.C., and bequeathed the throne to his eldest son, Phraates I. Under the reign of the latter, the expansion of the Parthian kingdom began once more. The incursion of Antiochus III had interrupted the Arsacid control of that part of the province of Parthia which lies south of the Alburz Range around Damghan and Shahrud. Phraates I not only reasserted Parthian jurisdiction up to the Caspian Gates, but even beyond; for he was able to establish a garrison of Mardians, tribesmen of Mazandaran, at the strongpoint of Charax immediately on the western side of the Gates. Thus he prepared the way for the Parthian advance into the province of Media, still at this period a strongly held outpost of the Seleucid empire with its headquarters at Ecbatana, the modern Hamadan. However, the conquest of Media for the Parthian kingdom was to remain a task for his son and successor, the mighty Mithradates I, whose accession to the throne is reckoned to have taken place in about 171 B.C, and who is to be considered the real author of Parthian expansion to the rank of a world-empire.
Andragoras and Commencement of Parthian Era
