-in-law, by undertaking some great military enterprise. The conquest of Greece was suggested to him, and he appointed a commission to make inquiries and report to him on the state of the country. But meanwhile his attention was distracted in another direction. For some hundred years, beginning about B.C. 650, Asia had suffered from invasions of northern races, Cimmerians and Scythians. The former ravaged the country from north to south, and even when defeated—as they were by the Cilicians—maintained themselves in mountain fastnesses from which they continued their devastations. The last invasion of Scythians, who were said to be pursuing the Cimmerians, had lasted twenty-eight years—from about B.C. 585 to 557—and it was uncertain when the danger might recur, Darius therefore determined to take the offensive and invade the country to the north of the Black Sea. This is one motive assigned to the "Scythian expedition," and it is not certainly disproved by showing that the invaders of Asia were not those whom he attacked. The Persians would have no certain knowledge of the difference between Scythian tribes. Their object would be to show their power in these northern regions from which they were reported to have come. But another object, no doubt, was—as shown in the sequel—to prevent help coming from European Greeks across the Hellespont to his Greek subjects in northern Asia Minor.
The story of this expedition (between B.C. 515–509) is given by Herodotus, probably from accounts which he found current in the northern Greek colonies. He may have learnt something also from the speech
