The Turkic dynasty that built a great sultanate across Persia and the Near East and, by winning Manzikert, opened Anatolia to the Turks.
The dynasty took its name from Seljuk, a chief of the Oghuz Turks who converted to Islam on the Central Asian steppe around 1000. His grandsons Tughril Beg and Chaghri Beg led their followers into Persia, defeating the Ghaznavids and overrunning the region.
In 1055 Tughril Beg entered Baghdad, freed the Abbasid caliph from the control of the Shia Buyids, and was recognised as sultan — temporal protector of Sunni Islam under the caliph’s spiritual authority.
Tughril’s nephew Alp Arslan expanded the empire into Armenia and Syria. In 1071 he met the Byzantine emperor Romanos IV at the Battle of Manzikert and won a crushing victory, capturing the emperor himself.
Manzikert broke Byzantine control of Anatolia and opened the interior to Turkish settlement — one of the decisive battles of the Middle Ages, whose consequences reached to the Crusades and the eventual rise of the Ottomans.
Under Malik-Shah I the Great Seljuk Empire reached its height, stretching from the borders of China to the Mediterranean. Much of the credit belongs to his brilliant Persian vizier Nizam al-Mulk, who built a network of madrasas, reformed the administration, and wrote a famous manual of statecraft.
This was an age of Persian cultural flowering under Turkish rule, associated with the poet and astronomer Omar Khayyam and the reform of the calendar.
After Malik-Shah’s death in 1092 the empire fragmented among rival princes and Turkish commanders, and it was in this divided world that the First Crusade arrived in 1096. The Great Seljuk sultanate faded in the twelfth century, though a Seljuk branch ruled the Sultanate of Rum in Anatolia for longer.
The Seljuks left a lasting mark: they entrenched Sunni Islam and the madrasa, spread Persian administrative culture, and — above all — turned Anatolia into the Turkish land it has been ever since.