It has all the appearance of being a well-laid plan, conceived by a moderate and wise prince, for the furtherance of a great design, and the permanent advantage of his empire.

The lord of South-Western Asia was well aware of the existence beyond his northern frontier of a standing menace to his power.

A century had not sufficed to wipe out the recollection of that terrible time when Scythian hordes had carried desolation far and wide over the fairest of the regions that were now under the Persian dominion.

What had occurred once might recur.
Possibly, as a modern author suggests, "the remembrance of ancient injuries may have been revived by recent aggressions." It was at any rate essential to strike terror into the hordes of the Steppe Region in order that Western Asia might attain a sense of security.

It was still more essential to do so if the north-west was to become the scene of war, and the Persians were to make a vigorous effort to establish themselves permanently in Europe.