It is no doubt a commonplace to state that Western Civilization is an heir, one among several, of an anterior unity: Christian Mediterranean Civilization. In that earlier unity all the local cultures that had sprung up round the great central sea — Egyptian, Mesopotamian, Anatolian, Aegean, Syrian, Iranian, Hellenic, Italic — had coalesced in three successive and increasingly comprehensive phases within the corresponding imperial frameworks of the pax achaemenia, the pax macedonica, and the pax romana. With the advent of Christianity this political and cultural amalgam passed into still another phase, that of the pax christiana, which fell heir also to the hitherto seclusive cultural tradition of the Jews. But, before this last phase was reached, the rhythm of history had changed from gathering to scattering; Iran, which once itself had contributed to the cultural syncretism of the Mediterranean world, and which can be regarded as that world's easternmost bastion, withdrew from it under the impact of the ‘neo-Achaemenian’ and anti-Hellenic reaction which inaugurated the Sassanian age. Iran was to remain hostile to the pax romana and, although Christian enclaves were to be established in its territory, outside the new unity of Christendom. But, even though withdrawn back to the pre-Hellenistic phase of history — as if Alexander the Great had never lived — New Iran exercised, chiefly through Syria, a profound influence, especially in art, upon the rest of the Mediterranean world, both before and after the ushering in of the pax christiana. With time, the disintegration begun in Iran spread. Christian Mediterranean Civilization was broken up and succeeded by several others that derived from it: that of the West was one, that of Byzantium another, and so also that of Christian Caucasia.