History of Christianity
The Church in the Early Middle Ages saw a "transformation of the Roman world" rather than a "fall of the Roman Empire". With the Muslim invasions of the seventh century, the Western (Latin) and Eastern (Greek) areas of Christianity began to take on distinctive shapes, and the Bishops of Rome were more interested in barbarian kings than in the Byzantine Emperors. This led to the coronation of Charlemagne as "Emperor of the Romans" by Pope Leo III in Rome on Christmas Day, 800.