During the reign of Roman emperor Heraclius in the early 7th century, he changed the empire’s official language from Latin to Greek. As the eastern half of the Mediterranean has always been predominantly Greek, the eastern half of the Roman Empire gradually became Hellenized following the fall of its Western Counterpart. Over the course of the following centuries, mainland Greece was mainly contested between the Roman and Bulgarian Empires, and suffered from invasions by Slavic tribes and Normans. Crete and Cyprus were contested between the Romans and Arabs and were later taken by the Crusaders, who following the Sack of Constantinople in 1204 established the Latin Empire in Thrace and Greece. The Romans retook Constantinople and re-established control in most of the Greek peninsula, although Epirus would remain an independent splinter state until the early 14th century when Roman control was re-established. As a civil war raged within the empire, the Serbian Empire took the opportunity to conquer most of mainland Greece while a resurgent Bulgarian Empire invaded from the north. In the century that followed, the Ottoman Empire would establish its dominance in the region annexing all three empires, finishing its conquest of Greece with the fall of the Morea in 1460.