Division of the Roman Empire
Emperor Diocletian, who ruled from A.D. 284 to 305, divided the administration of Rome into four areas ruled by four caesars. Though the scheme was never completely successful because of rivalries among the caesars, it led to the division of the empire into two major and eventually permanent divisions. When Constantine gained control of the eastern major region (as well as the western one, which he originally ruled), he moved his capital from Rome to his own new city in the east, Byzantium, renamed Constantinople, which was on the strait between the Black Sea and the Sea of Marmara that demarks the border between Europe and Asia. Constantinople was, at that time, in the territory of ancient Greece, and is now in Turkey.
fallacy
Though many social commentators have claimed that civilizations seldom survive three or four centuries (the approximate lifespan of ancient Greece and of the western Roman Empire), historians sympathetic to the eastern Roman Empire contend that it actually improved after four centuries and continued intact for fully a thousand years. The eastern Roman Empire and its churches had no “dark ages.”
Under Theodosius I, who ascended Constantine's throne after him, the division became officially permanent. But while the west, administered from Rome, got weaker and was overrun by Germanic tribes, the eastern empire, which always called itself “the Roman empire” but which those in Rome have called “the Byzantine Empire,” thrived and continued to be generally stable for a millennium after Constantine.
Greek became the language of the eastern empire, with Latin continuing as the official tongue in the west. Eventually, this division led to a division of the Catholic Church, between western (Latin) under the supreme magisterium of the bishop of Rome, and eastern (Greek) Christendom that continued under a pluralism of bishops of equal power throughout the far-flung empire.
