Seljuks, members of the ruling family of Ouz Turkmen tribes. The warlike and nomadic Seljuks originated in Turkestan, in central Asia, and were named for Seljuk, their first leader. The Seljuks invaded western Asia in the mid-11th century. By 1092 they controlled most of Iran and all of Mesopotamia, Syria, and Palestine. But the Seljuks' territory soon was splintered into small states, one of which, in Anatolia, gave rise to the Ottoman Turks and the modern Turkish state. During the Crusades of the 11th, 12th, and 13th centuries, the Islamic Seljuks defended the Holy Land against the European Christians.