In the second half of the ninth century the Carolingian world gradually disintegrated. After the creation of three independent kingdoms (Treaty of Verdun) further divisions occurred, and central authority all but disappeared. Economic contraction and military impotence accompanied political disintegration. Europe became increasingly vulnerable to military attacks. Viking raids at the beginning of the ninth century turned into more permanent invasions in the second half of the century, with Vikings settling in Ireland, Frisia, England, Normandy and elsewhere. In the East the Magyars went on plundering sprees, until Otto the Great (936–73) called a halt to it (in 955). In Southern Europe, Islamic incursions into the Mediterranean islands (Sicily, the Balearic Islands), and south of France and Italy, further disclosed the weakness of Europe.

The Church too, during the tenth and eleventh centuries, suffered decline. In a climate of economic downturn simony was epidemic, while local potentates seized Church property. During the tenth and early eleventh century, the papacy became an economic commodity, to be bought and sold, by rivalling Roman families. The colourful, infamous career of Pope John XII (955–63) represents the low point of the papacy at that time.