Westerners called the people ruling that portion of the Roman Empire centered on Constantinople in the east (which survived until 1453 AD.) "Greeks," who in turn called the Westerners "Franks." Nowadays we call the later East Romans the "Byzantines." They called themselves "Romans," which they were (despite speaking Greek) and had been since the 4th Century. That was when the Roman Empire was assailed on all sides by German and other invaders. The western portions of the empire succumbed to the barbaian tide in the 5th Century. But the eastern portion (which spoke Greek and Latin) withstood the Germans, the Arabs and, until 1453, the Turks. There was a lot of ill-will between the Byzantines (who saw the Westerners as crude barbarians) and Westerners (who saw the Byzantines as arrogant and slippery), and for about 60 years after the Fourth Crusade (1204) the "Franks" actually held Constantinople. The Byzantines recovered, but they were badly injured, and the remaining two centuries of their history was one of steady decline.