REIGN OF CYRUS THE GREAT (558-529 B.C.).--The leader of the revolt against the Medes was Cyrus, the tributary king of the Persians. Through his energy and soldierly genius, he soon built up an empire more extended than any over which the sceptre had yet been swayed by an Oriental monarch, or indeed, so far as we know, by any ruler before his time. It stretched from the Indus to the farthest limits of Asia Minor, and from the Caspian Sea to the Persian Gulf, thus embracing not only the territories of the Median kingdom, but also those of the allied kingdoms of Lydia and Babylonia. The subjugation of Babylonia to the Persian authority has already been narrated (see p. 60). We will now tell how Cyrus gained the kingdom of Lydia. [Illustration: KINGDOMS OF LYDIA, MEDIA, AND BABYLONIA. C. B.C. 550] Lydia was a country in the western part of Asia Minor. It was a land highly favored by nature. It embraced two rich river valleys,--the plains of the Hermus and the Cayster,--which, from the mountains inland, slope gently to the island-dotted Aegean. The Pactolus, and other tributaries of the streams we have named, rolled down "golden sands," while the mountains were rich in the precious metals. The coast region did not at first belong to Lydia; it was held by the Greeks, who had fringed it with cities. The capital of the country was Sardis, whose citadel was set on a lofty and precipitous rock. The Lydians were a mixed people, formed, it is thought, by the mingling, in prehistoric times, of Aryan tribes that crossed the Aegean from Europe, with the original non-Aryan population of the country. The last and most renowned of the Lydian kings was Croesus. Under him the Lydian empire attained its greatest extension, embracing all the states of Asia Minor west of the Halys, save Lycia. The tribute Croesus collected from the Greek cities, which he subjugated, and the revenues he derived from his gold mines, rendered him the richest monarch of his times, so that his name has passed into the proverb "Rich as Croesus." Now Astyages, whom Cyrus had just overthrown, was the brother-in-law of this Croesus. When Croesus heard of his relative's misfortune, he resolved to avenge his wrongs. The Delphian oracle (see p. 104), to which he sent to learn the issue of a war upon Cyrus, told him that he "would destroy a great kingdom." Interpreting this favorably, he sent again to inquire whether the empire he should establish would prove permanent, and received this oracle: "Flee and tarry not when a mule [Footnote: The allusion is to the (traditional) mixed Persian and Median descent of Cyrus.] shall be king of the Medes." Deeming the accession of a mule to the Persian throne altogether impossible, he inferred the oracle to mean that his empire should last forever.