The Middle Ages mark the transition between ancient and modern times in western Europe. During the Middle Ages, Christianity, the Greek and Roman heritage, and the culture of Germanic invaders combined to create a new western European civilization. Charlemagne, a Germanic king, became Holy Roman emperor in A.D. 800 and united western Europe for the first time since the fall of Rome. During the Middle Ages the Roman Catholic Church exercised strong religious and political influence over western Europe. After Charlemagne's death, feudalism, a new type of social organization, emerged to provide order and protection. Central government and trade declined. Gradually, however, monarchies were strengthened. In England, however, Parliament placed limits on royal power and played a key role in passing laws.