The document discusses feudal Europe, beginning with the Carolingian Empire established by Charlemagne in the 8th century. After Charlemagne's death, the empire was divided among his grandsons. It then describes the second wave of invasions from Vikings, Magyars, and Muslims in the 9th-10th centuries, which weakened royal authority. This led to the rise of feudalism, a political and economic system where kings granted land to nobles who provided military service, and nobles granted land to knights and vassals, who also provided service. Feudal society was divided into three estates - nobility, clergy, and peasants - and was based around a rural, self-sufficient