The fourth century witnessed the split of the Roman Empire into two distinct empires: the Eastern Roman Empire (later called the Byzantine Empire) and Western Roman Empire, a split reinforced when Constantine I transferred the capital of the Eastern Empire from Nicomedia (in Anatolia) to Byzantium (the city which inspired his imagination in 330 AD to be rebuilt as Nuova Roma (New Rome) ). After Constantine's death, Byzantium had been called Constantinople ('City of Constantine'), until it fell under the Ottoman Empire on May 29, 1453, by then the Turks named it 'Istanbul'.
The Byzantine Empire had an evident character of Greco-Roman civilization. Significantly, when the Byzantines gradually embraced Christianity, during the 5th and 6th centuries, their culture acquired a noticeably distinct character, different from their pagan past. By the 7th century, the empire was channeled into another direction under the rule of Emperor Heraclius, when Greek was made the official language of the empire and improvements were made within the military. When its links with the old Greco-Roman world scattered, the Byzantine Empire finally started to acquire an 'Oriental' style, a style considerably strengthened by the 15th century, after the fall of Constantinople under the Ottoman Turks in the wake of a long state of deterioration that had struck the Byzantine Empire in the 12th century.
Even when struck with recurrent setbacks, the Byzantine Empire eagerly preserved its economic, cultural and military position inside the continent through providing a military shield against early Muslim expansion; supplying the Mediterranean area with gold currencies; and imposing its influence on the political systems, laws , and customs of Europe, an influence which further spread into North Africa and the Near East for much of the Middle Ages.