Originally nomads from the Turkistan region of central Asia. During the 6th century ad they controlled an empire stretching from Mongolia to the Caspian Sea. With the conquest of western Turkistan in the 7th century by the Abbasids, many were converted to Islam and moved westwards, retaining their distinctive language and culture. In the 11th century, under the Seljuks they replaced the Arabs as rulers of the Levant and Mesopotamia, then expanded north‐west at the expense of Byzantium. The rival house of Osman continued this trend, founding the Ottoman empire, which endured for 600 years, and embraced most of the Middle East, North Africa, and the Balkans.