The duration of a single unbroken empire continuously for 1306 (or 1360) years, which is the time assigned to the Assyrian Monarchy by Ctesias, must be admitted to be a thing hard of belief, if not actually incredible.  The Roman State, with all its elements of strength, had (we are told), as kingdom, commonwealth, and empire, a duration of no more than twelve centuries.  The Chaldaean Monarchy lasted, as we have seen, about a thousand years, from the time of the Elamite conquest.  The duration of the Parthian was about five centuries of the first Persian, less than two and a half; of the Median, at the utmost, one and a half; of the later Babylonian, less than one.  The only monarchy existing under conditions at all similar to Assyria, whereto an equally long—­or rather a still longer—­duration has been assigned with some show of reason, is Egypt.  But there it is admitted that the continuity was interrupted by the long foreign domination of the Hyksos, and by at least one other foreign conquest—­that of the Ethiopian Sabacos or Shebeks.  According to Ctesias, one and the same dynasty occupied the Assyrian throne during the whole period, of thirteen hundred years.  Sardanapalus, the last king in his list, being the descendant and legitimate successor of Ninus.

There can be no doubt that a monarchy lasting about six centuries and a half, and ruled by at least two or three different dynasties, is per se a thing far more probable than one ruled by one and the same dynasty for more than thirteen centuries.  And therefore, if the historical evidence in the two cases is at all equal—­or rather, if that which supports the more improbable account does not greatly preponderate—­we ought to give credence to the more moderate and probable of the two statements.

Now, putting aside authors who merely re-echo the statements of others, there seem to be, in the present case, two and two only distinct original authorities—­Herodotus and Ctesias.  Of these two, Herodotus is the earlier.  He writes within two centuries of the termination of the Assyrian rule, whereas Ctesias writes at least thirty years later.  He is of unimpeachable honesty, and may be thoroughly trusted to have reported only what he had heard.  He had travelled in the East, and had done his best to obtain accurate information upon Oriental matters, consulting on the subject, among others, the Chaldaeans of Babylon.  He had, moreover, taken special pains to inform himself upon all that related to Assyria, which he designed to make the subject of an elaborate work distinct from his general history.