But what caused Media to be at war with the distant land of Lydia? We must assume that Cyaxares first succeeded in setting his land free from the hordes of the Sacæ. He availed himself of this to give aid to the lands bordering on the west of Media, the Armenians and Cappadocians, against the same plundering tribes; to exhibit himself there as a liberator from the Sacæ; and, at the same time, as a liberator from the dominion of the Assyrians. In this way he quickly advanced the borders of Media to the Halys. Here he came upon the Lydians, who on their part had made use of the convulsion and confusion which had been caused by the advance of the Cimmerians as far as the western shore of Asia Minor, to extend their dominion over Phrygia as far as the Halys. As the war between him and the Lydians commences in the year 615 B.C., Cyaxares must have mastered the Sacæ in Media as early as the year 620 B.C. The dominion of the Scythians in Asia, which Herodotus represents as lasting 28 years, is thus narrowed down to a short ten years--or indeed to eight years, the number given by Justin. From this point--the liberation of Media from the Sacæ, _i.e._ about 620 B.C.,--we have to fix not only the advance of Cyaxares to the West, but his league with Nabopolassar of Babylon, and the marriage of his daughter to Nabopolassar's son must be put about the same time. When Nabopolassar had arranged the peace between Media and Lydia, which fixed the Halys as the border of the two kingdoms, Aryanis, the daughter of Alyattes, is married to the son of Cyaxares (610 B.C.), Media and Babylonia, Cyaxares and Nabopolassar, unite their forces against Assyria.