What events, passing in the far East among the divers groups of the Iranians themselves and their Scythian allies, led to this king of a district in Elam, whose own claim to have belonged by blood to any of those groups is doubtful, consolidating all the Iranians whether of the south or north under his single rule into a mighty power of offence, we do not know. Stories current among the Greeks and reported by Herodotus and Ctesias represented Cyrus as in any case a Persian, but as either grandson of a Median king (though not his natural heir) or merely one of his court officials. What the Greeks had to account for (and so have we) is the subsequent disappearance of the north Iranian kings of the Medes and the fusion of their subjects with the Persian Iranians under a southern dynasty. And what the Greeks did not know, but we do, from cuneiform inscriptions either contemporary with, or very little subsequent to, Cyrus' time, only complicates the problem; since these bear witness that Cyrus was known at first (as has been indicated already) for a king of Elam, and not till later for a king of Persia. Ctesias, who lived at Susa itself while at was the Persian capital, agrees with Herodotus that Cyrus wrested the lordship of the Medes from the native dynasty by force; but Herodotus adds that many Medes were consenting parties.
These problems cannot be discussed here. The probability is, summarily, this. Some part of the southern or Persian group of Iranians which, unlike the northern, was not contaminated with Scyths, had advanced into Elam while the Medes were overrunning and weakening the Semitic Empire; and in Anshan it consolidated itself into a territorial power with Susa for capital. Presently some disaffection arose among the northern Iranians owing, perhaps, to favour shown by the Median kings to their warlike Scythian subjects, and the malcontents called in the king of Anshan. The issue was fought out in central West Persia, which had been dominated by the Medes since the time of Kyaxares' father, Phraortes, and when it was decided by the secession of good part of the army of King Astyages, Cyrus of Anshan took possession of the Median Empire with the goodwill of much of the Median population. This empire included then, beside the original Median land, not only territories conquered from Assyria but also all that part of Persia which lay east of Elam. Some time, doubtless, elapsed before the sovereignty of Cyrus was acknowledged by all Persia; but, once his lordship over this land was an accomplished fact, he naturally became known as king primarily of the Persians, and only secondarily of the Medes, while his seat remained at Susa in his own original Elamite realm. The Scythian element in and about his Median province remained unreconciled, and one day he would meet his death in a campaign against it; but the Iranian element remained faithful to him and his son, and only after the death of the latter gave expression by a general revolt to its discontent with the bargain it had made.