This opposition of philosophy to the existing religion was often not explicit, and it did not concern religious practice. Even those philosophers whose theory left no room for the existence or at least the importance of the gods, continued to engage loyally in the established cults. But although the superstructure of religion remained, the foundation, to some extent at least, was undermined. In the second place, since religion in ancient Greece had been closely connected with the city-states, the destruction of the states brought important changes in religion. The Greek states lost their independence through the conquests of Philip of Macedon and Alexander the Great. Those conquests meant, indeed, a wide extension of Greek culture throughout the eastern world. But the religion of Alexander's empire and of the kingdoms into which it was divided after his death was widely different from the religion of Athens in her glory. Cosmopolitanism brought mighty changes in religion, as in the political sphere. In the third place, the influence of the eastern religions made itself more and more strongly felt. That influence was never indeed dominant in the life of Greece proper so completely as it was in some other parts of the world. But in general it was very important. When the Olympic gods lost their place in the minds and hearts of men, other gods were ready to take their place. Before any account can be given of the eastern religions taken separately, and of their progress toward the west, it may be well to mention certain general characteristics of the period which followed the conquests of Alexander. That period, which extended several centuries into the Christian era, is usually called the Hellenistic age, to distinguish it from the Hellenic period which had gone before. The Hellenistic age was characterized, in the first place, by cosmopolitanism. Natural and racial barriers to an astonishing extent were broken down; the world, at least the educated world of the cities, was united by the bonds of a common language, and finally by a common political control. The common language was the Koiné, the modified form of the Attic dialect of Greek, which became the vehicle of a world-civilization. The common political control was that of the Roman Empire. On account of the union of these two factors, inter-communication between various nations and races was safe and easy; the nations were united both in trade and in intellectual activity.