By 1040 the lands of Central Asia would pass from under the control of the Ghaznavids to that of the Seljuks. As the immediate forebears of the Ottomans, who would later come to dominate Asia Minor and the Mediterranean, the Seljuks established the Turks as a unified military force. Until the Seljuk empire provided cohesion to the Turks of Central Asia, the Turks had existed only in separate, nomadic groups. For much of the previous centuries of Islam's presence in Central Asia, Turks had been recruited as slaves for all regions of the Islamic empire. Turks were widely considered within the Islamic world to be superior soldiers, and their slavery was therefore usually in a military capacity. When the Seljuks unified the Turks of Central Asia, they became a formidable military force, first under the Seljuks themselves, and later under the Ottomans.

Despite their independence, the Seljuks, like many other regional Islamic dynasties, retained their allegiance to the Abbasid caliph in Baghdad. In 1050, the Seljuk leader, Tughril Beg, was awarded the title of Sultan from the Abbasid caliph, and he became the first Muslim ruler to use that title. It later became a common title for a Muslim ruler.

In the mid-11th century the Seljuks also began their assault on Byzantine-ruled Asia Minor. Initially, raids into Byzantine territory were intended only to deter the Byzantines from concluding an alliance with the Shi'ite Fatimids in Egypt and Syria, who were the Seljuks' enemies, but the raids soon acquired an expansionist zeal. In 1071, the Seljuks achieved a decisive victory against the Byzantines in the Battle of Manzikert, in Armenia. They captured the Byzantine emperor, Romanos Diogenes, and forced him to accept a peace treaty that in effect opened the door for Seljuk expansion into Asia Minor. In 1078, the Seljuks had reached Nicaea, near Constantinople, and the Seljuk sultan, Suleyman, moved his capital there. It was the first permanent Turkish settlement in Asia Minor, and the Turkish presence in the region has continued ever since. The rise of the Islamic Turks at the expense of the Greek Byzantines in Asia Minor is indeed one of the most significant demographic shifts of the medieval period. Numerous battles with the Christians ensued over the next few centuries, with each side trading small parcels of territory after each battle. The Seljuks were also involved in several Crusades, sometimes in allegiance with Western European countries against the Greek Byzantines, and they also faced the wrath of the invading Mongols in the 13th century.

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The Seljuks brought many diverse peoples - from India, Persia, Iraq, Armenia, and Asia Minor - under one sultan, and advanced the positions of both the Turks as an ethnic group and Sunnism as a distinct faith within Islam. This unity and monarchism changed the traditional lives of all Turks, and it had a particular effect on Turkish women. Converting to Islam meant that many Turkish women under the Seljuks took to the veil and were not involved in public life. In contrast, Turkish women on the Central Asian steppe had often fought alongside men, and had participated in community life to a similar degree as men.

The Mongol invasion in the 13th century marked the downfall of the Seljuk dynasty, as the Seljuks of Asia Minor came under the domination of the Mongols in Persia and Iraq. As the Seljuks slowly faded from the scene, a new group of Turks began to organise themselves in Asia Minor. Named after the Osman family, these Ottoman Turks began raiding Byzantine lands in western Asia Minor in the early 14th century. Before long, the Ottomans had grown into the largest and most powerful Islamic empire, and one of the most powerful empires of any religion, in the world.