The Turkish migrations after the sixth century were part of a general movement of people out of central Asia during the first millennium A.D. that was influenced by a number of interrelated factors–climatic changes, the strain of growing populations on a fragile pastoral economy, and pressure from stronger neighbors also on the move. Among those who migrated were the Oguz Turks, who had embraced Islam in the tenth century. They established themselves around Bukhara in Transoxania under their khan, Seljuk.
Split by dissension among the tribes, one branch of the Oguz, led by descendants of Seljuk, moved west and entered service with the Abbasid caliphs of Baghdad.
The Turkish horsemen, known as gazis , were organized into tribal bands to defend the frontiers of the caliphate, often against their own kinsmen. However, in 1055 a Seljuk khan, Tugrul Bey, occupied Baghdad at the head of an army composed of gazis and mamluks (slave-soldiers, a number of whom became military leaders andrulers). Tugrul forced the caliph (the spiritual leader of Islam) to recognize him as sultan, or temporal leader, in Persia and Mesopotamia. While they engaged in state building, the Sel…. also emerged as the champions of Sunni Islam against the religion’s Shia sect. Tugrul’s successor, Mehmet ibn Daud (r. 1063-72)–better known as Alp Arslan, the “Lion Hero”–prepared for a campaign against the Shia Fatimid caliphate in Egypt but was forced to divert his attention to Anatolia by the gazis , on whose endurance and mobility the Sel…. depended.
The Seljuk elite could not persuade these gazis to live within the framework of a bureaucratic Persian state, content with collecting taxes and patrolling trade routes. Each year the gazis cut deeper into Byzantine territory, raiding and taking booty according to their tradition. Some served as mercenaries in the private wars of Byzantine nobles and occasionally settled on land they had taken. The Sel…. followed the gazis into Anatolia in order to retain control over them. In 1071 Alp Arslan routed the Byzantine army at Manzikert near Lake Van, opening all of Anatolia to conquest by the Turks.
Armenia had been annexed by the Byzantine Empire in 1045, but religious animosity between the Armenians and the Greeks prevented these two Christian peoplefrom cooperating against the Turks on the frontier. Although Christianity had been adopted as the official religion of the state around A.D. 300, nearly 100 years before similar action was taken in the Roman Empire, Armenians were converted to a form of Christianity at variance with the Orthodox tradition of the Greek church, and they had their own patriarchate independent of Constantinople. After their conquest by the Sassanians around 400, their religion bound them together as a nation andprovided the inspiration for a flowering of Armenian culture in the fifth century. When their homeland fell to the Sel…. in the late eleventh century, large numbers of Armenians were dispersed throughout the Byzantine Empire, many of them settling in Constantinople, where in its centuries of decline they became generals andstatesmen as well as craftsmen, builders, and traders.