Europe's antiquity dates from the Minoan civilization, the Myceneans and later on Homer's "Iliad" in Ancient Greece of around 700 BC. The Roman Republic was established in 509 BC, which was usurped by Octavian's new Roman Empire at its first century BC peak. The Christian religion was adopted in the fourth century, and in the sixth was organized, within the Empire, by Emperor Justinian I (527–565) with five most important cities: Rome, Constantinople, Antioch, Jerusalem and Alexandria. The fall of the Western Roman Empire was followed by a decline of Western Europe. The Byzantine Empire survived in the East. A new schism within the church's authority in 1054 was added to the earlier division that had persisted since 451. It was followed by Crusades from west to rescue the Holy Land from Muslim invasion. Feudal society began to break down, as the Black Death spread.