The Cambridge History of India, Vol. I: Ancient India v1.c26.268

v1.c26.268

Another point about which there is practical unanimity is that the revolt of Parthia took place almost simultaneously with the revolt of Bactria, although probably a year or two later. The explanation lies on the surface: Antiochus II (261–246) like his two immediate successors, Seleucus II (246–226) and Seleucus III (226–223), was too much preoccupied with wars and rumours of wars in the west to maintain a proper hold over his eastern dominions. Probably, too, there were other causes at work. The spectacle of the greatness of the Maurya empire would not be lost upon a satrap of such force of character as the elder Diodotus. And in his case to the promptings of ambition there may have been added a spur of a different kind. It is not unlikely that Bactria was already beginning to be conscious, on her northern border, of the first onset of the pressure before which she was in the end to succumb; Eastern Asia was just entering upon one of those mysterious convulsions of tribal unrest, which produced the great migrations, and of which the Parthian revolt itself was not impossibly a manifestation. If this were so, Diodotus may well have felt that an independent kingdom, strong in its new-born sense of national unity, was likely to be a more permanent bulwark against barbarian aggression than the loosely attached extremity of an empire whose head was in no position to afford efficient protection to his nominal subjects. Besides the native Iranian basis on which he would have to build, the descendants of Alexander's colonists would provide him with a substantial Hellenic framework ready to hand; and, as a matter of fact, Bactria was, throughout the whole of its brief career, essentially an Hellenic state. In this connexion it is significant to note that, under the earlier Diodotus, Parthia was a potential, if not an actual, enemy. Justin tells us, in the chapter that has been so often quoted, that 'fear of Diodotus' was one of the chief motives that led Arsaces, after his seizure of Hyrcania, to keep a great army on a war-footing. He goes on to say that, when the old satrap died, his son reversed his Parthian policy, and concluded an alliance which set Arsaces free to concentrate his whole forces against Seleucus II, then advancing eastwards on a futile campaign of reconquest. The threat of a renewal of the Macedonian supremacy was enough to bring Greek and barbarian together. The eastern expedition of Seleucus II was subsequent to the battle of Ancyra, in which he was heavily defeated by the Gauls (240 B.C.). It cannot, therefore, have taken place earlier than 238, and it can hardly be put later than 235. This gives us something approaching a definite date at which Diodotus II was on the throne of Bactria.