In the history of Europe, the Middle Ages or medieval period lasted approximately from 500 AD to 1500, although some prefer other start and end dates. The Middle Ages is the second of the three traditional divisions of Western history: antiquity, medieval, and modern. Major developments include the predominance of agriculture in the economy, the exploitation of the peasantry, slow interregional communication, the importance of personal relationships in power structures, and the weakness of state administration. The period is sometimes subdivided into the Early, High, and Late Middle Ages, and the early medieval period is alternatively referred to as the Dark Ages.
Population decline, counterurbanisation, the collapse of centralised authority, the mass migration of tribes (mainly Germanic peoples), and Christianisation, which had begun in late antiquity, continued into the Early Middle Ages. The movements of peoples led to the disintegration of the Western Roman Empire, and the rise of new kingdoms. In the post-Roman world, taxation declined, the army was financed through land grants, and the blending of Later Roman civilisation and the invaders' traditions is well documented. The Eastern Roman Empire (or Byzantine Empire) survived but lost the Middle East and North Africa to Muslim conquerors in the . Although the Carolingian dynasty of the Franks reunited much of the Western Roman lands by the early , the Carolingian Empire quickly fell apart into competing kingdoms, which later fragmented into autonomous duchies and lordships.
During the High Middle Ages, which began after 1000, the population of Europe increased greatly as the Medieval Warm Period allowed crop yields to increase, and technological and agricultural innovations introduced a "commercial revolution". Slavery nearly disappeared, and peasants could improve their status by colonising faraway regions in return for economic and legal concessions. New towns developed from local commercial centers, and urban artisans united into local guilds to protect their common interests. Western church leaders accepted papal supremacy to get rid of lay influence, which accelerated the separation of the western Catholic and eastern Orthodox Churches, and triggered the Investiture Controversy between the papacy and secular powers. With the spread of heavy cavalry, a new aristocracy emerged who stabilised their position through strict inheritance customs. In the system of feudalism, the noble knights owed military service to their lords in return for the lands they had received in fief. Stone castles were built in regions where central authority was weak, but by the end of the period state power was on the rise. The settlement of Western European peasants and aristocrats towards the eastern and southern peripheries of Europe, often spurred by crusades, led to the expansion of Latin Christendom against the neighbouring Muslim, pagan, and Orthodox peoples. The spread of cathedral schools and universities stimulated a new method of intellectual discussion, with an emphasis on rational argumentation, known as scholasticism. Mass pilgrimages prompted the construction of massive Romanesque churches, while structural innovations led to the development of the more delicate Gothic architecture.
