After 1054 and the death of Yaroslav, Kievan Russia began to decline, torn apart by rivalries between various city-states. Turkic nomads, by then a powerful force in Eastern Europe, became more involved in Russian affairs, and in 1097 a group of Russian nobles divided the empire with them. This would make Russia
Particularly vulnerable to the Mongol invasion about 150 years later.
The year 1054 also marked a turning point for Eastern Europe as a whole. It was then that the Eastern Orthodox Church formally broke with Rome over a number of issues, including clerical celibacy—that is, the question of whether priests could marry. Orthodox leaders held that they could and should; Rome, particularly after the split with the Orthodox Church, opposed marriage for priests.
Soon afterward, Byzantium experienced another, even more significant, turning point: its loss to the Turks at the Battle of Manzikert in Armenia in 1071. The Turks even took the Byzantine emperor prisoner, and soon afterward helped themselves to all of Asia Minor, thenceforth known as Turkey. Thus less than fifty years after the victories of Basil II, Byzantium lost everything it had gained, and though the empire would continue for three more centuries, Manzikert was a blow from which it would never recover.
World History
