The evidence both of the classical writers and of the monuments is to the effect that exact chronology was a subject to which the Babylonians and Assyrians paid great attention.

The "Canon of Ptolemy," which contained an exact Babylonian computation of time from B.C.747 to B.C.331, is generally allowed to be a most authentic document, and one on which we may place complete reliance.

The "Assyrian Canon," which gives the years of the Assyrian monarchs from B.C.911 to B.C.660, appears to be equally trustworthy.

How much further exact notation went back, it is impossible to say.

All that we know is, first, that the later Assyrian monarchs believed they had means of fixing the exact date of events in their own history and in that of Babylon up to a time distant from their own as much as sixteen or seventeen hundred years; and secondly, that the chronology which result from their statements and those of Berosus is moderate, probably, and in harmony with all the knowledge which we obtain of the East from other sources.