It is just possible that they may have taken an interest in the warfare of their southern brethren, and that, when Cyaxares brought the tribes of Zagros under his yoke, the Scyths of the north may have felt resentment, or compassion, If this view seem too improbable, considering the distance, the physical obstacles, and the little communication that there was between nations in those early times, we must suppose that by a mere coincidence it happened that the subjugation of the southern Scyths by Cyaxares was followed within a few years by a great irruption of Scyths from the trans-Caucasian region.

In that case we shall have to regard the invasion as a mere example of that ever-recurring law by which the poor and hardy races of Upper Asia or Europe are from time to time directed upon the effete kingdoms of the south, to shake, ravage, or overturn them, as the case may be, and prevent them from stagnating into corruption.
The character of the Scythians, and the general nature of their ravages, have been described in a former portion of this work.

If they entered Southern Asia, as seems probable, by the Daghestan route, they would then have been able to pass on without much difficulty, through Georgia into Azerbijan, and from Azerbijan into Media Magna, where the Medes had now established their southern capital.

Four roads lead from Azerbijan to Hamadan or the Greater Ecbatana, one through Menjil and Kasvin, and across the Caraghan Hills; a second through Miana, Zenjan, and the province of Khamseh; a third by the valley of the Jaghetu, through Chukli and Tikan-Teppeh; and a fourth through Sefer-Khaneh and Sennah.
We cannot say which of the four the invaders selected; but, as they were passing southwards, they met the army of Cyaxares, which had quitted Nineveh on the first news of their invasion, and had marched in hot haste to meet and engage them.

The two enemies were not ill-matched.
Both were hardy and warlike, both active and full of energy; with both the cavalry was the chief arm, and the bow the weapon on which they depended mainly for victory.