that threatened its existence, as the Gallic and Palmyrene Empires broke away from the Roman state, and a series of short-lived emperors, often from the legions, led the Empire. It was reunified under Aurelian (). To stabilize it, Diocletian set up two different imperial courts in the Greek East and Latin West in 286; Christians rose to positions of power in the 4th century following the Edict of Milan of 313. Shortly after, the Migration Period, involving large invasions by Germanic peoples and by the Huns of Attila, led to the decline of the Western Roman Empire. With the fall of Ravenna to the Germanic Herulians and the deposition of Romulus Augustus in AD 476 by Odoacer, the Western Roman Empire finally collapsed; the Eastern Roman emperor Zeno formally abolished it in AD 480. The Eastern Roman Empire survived for another millennium, until Constantinople fell in 1453 to the Ottoman Turks under Mehmed II. Due to the Roman Empire's vast extent and long endurance, the institutions and culture of Rome had a profound and lasting influence on the development of language, religion, art, architecture, literature, philosophy, law, and forms of government in the territory it governed. The Latin language of the Romans evolved into the Romance languages of the medieval and modern world, while Medieval Greek became the language of the Eastern Roman Empire. The Empire's adoption of Christianity led to the formation of medieval Christendom. Roman and Greek art had a profound impact on the Italian Renaissance. Rome's architectural tradition served as the basis for Romanesque, Renaissance and Neoclassical architecture, and also had a strong influence on Islamic architecture. The rediscovery of Greek and Roman science and technology (which also formed the basis for Islamic science) in Medieval Europe led to the Scientific Renaissance and Scientific Revolution. The corpus of Roman law has its descendants in many modern legal systems of the world, such as the Napoleonic Code of France, while Rome's republican institutions have left an enduring legacy, influencing the Italian city-state republics of the medieval period, as well as the early United States and other modern democratic republics. History Transition from Republic to Empire Rome had begun expanding shortly after the founding of the Roman Republic in the 6th century BC, though it did not expand outside the Italian peninsula until the 3rd century BC. Then, it was an "empire" (i.e., a great power) long before it