The conquest of the Ionian cities, first by Croesus and then by Cyrus, was attended with important political consequences. Before the time of Croesus the Greek cities of Asia were independent. Had they combined together for offence and defence, with the assistance of Sparta and Athens, they might have resisted the attacks of both Lydians and Persians. But the autonomy of cities and states, favorable as it was to the development of art, literature, and commerce, as well as of individual genius in all departments of knowledge and enterprise, was not calculated to make a people politically powerful. Only a strong central power enables a country to resist hostile aggressions on a great scale. Thus Greece herself ultimately fell into the hands of Philip, and afterward into those of the Romans. The conquest of the Ionian cities also introduced into Asia Minor and perhaps into Europe Oriental customs, luxuries, and wealth hitherto unknown. Certainly when Persia became an irresistible power and ruled the conquered countries by satraps and royal governors, it assimilated the Greeks with Asiatics, and modified the forms of social life; it brought Asia and Europe together, and produced a rivalry which finally ended in the battle of Marathon and the subsequent Asiatic victories of Alexander. While the conquests of the Persians introduced Oriental ideas and customs into Greece, the wars of Alexander extended the Grecian sway in Asia. The civilized world opened toward the East; but with the extension of Greek ideas and art, there was a decline of primitive virtues in Greece herself. Luxury undermined power. The annexation of Asia Minor to the empire of Cyrus was followed by a protracted war with the barbarians on his eastern boundaries. The imperfect subjugation of barbaric nations living in Central Asia occupied Cyrus, it is thought, about twelve years. He pushed his conquests to the Iaxartes on the north and Afghanistan on the east, reducing that vast country which lies between the Caspian Sea and the deserts of Tartary.