The Great Seljuk Empire or the Seljuk Empire, was a high medieval Turko-Persian Sunni Muslim empire, originating from the Qiniq branch of Oghuz Turks. At the time of its greatest extent, the Seljuk Empire controlled a vast area, stretching from western Anatolia and the Levant in the west to the Hindu Kush in the east, and from Central Asia in the north to the Persian Gulf in the south.
The Seljuk empire was founded in 1037 by Tughril and his brother Chaghri. From their homelands near the Aral Sea, the Seljuks advanced first into Khorasan and then into mainland Persia, before eventually conquering Baghdad and eastern Anatolia. The Seljuks won the battle of Manzikert in 1071, and then conquered most of the rest of Anatolia, wresting it from the Byzantine Empire. This was one of the impetuses for the First Crusade. The Seljuk empire began to decline in the 1140s, and by 1194 had been supplanted by the Khwarazmian Empire.
Seljuk gave his name to both the empire and the Seljuk dynasty. The Seljuk empire united the fractured political landscape of the eastern Islamic world and played a key role in both the First Crusade and Second Crusade.