Tutush I ibn Alp Arslān was Saljûq king (Arab. malik) of Syria (1078-1095), with the title Taj al-Dawla (Crown of the State), ruling under the overlordship of his brother the Great Saljûq sultan Malik Shāh I (d. 1092).
Tutush was a son of Sultan Alp Arslān (d. 1072), whose armies conquered Syria from the Fātimids of Egypt in the years 1070-1075. His appointment as ruler came about after the defeat of Atsiz ibn Uwaq, the Saljûq commander of southern Syria and Palestine, by the Fātimids at Cairo (February 1077) and the ensuing rebellions against Saljûq rule in Palestine. At this time Malik Shāh I was busy fighting a civil war in Persia, but wanted to ensure continuing Saljûq rule of Syria and Palestine, and ultimately, a successful invasion of Egypt and the ending of the Fātimid Shī‘ite caliphate.
Tutush came to Syria in 1078. He executed Atsiz ibn Uwaq and took control of Damascus and most of Palestine, including Jerusalem and the important coastal cities of Jaffa (mod. Yel Aviv-Yafo) and Sidon (mod. Saïda, Lebanon). In his government the young king depended on several Turcoman officers, notably his faithful commander Zāhir al-Dīn Tughtigin, who acted as his deputy. Tutush did not gain control of all of inland Syria until May 1094, when he finally captured Aleppo. He established a modus vivendi with the ruling dynasties of Tyre (mod. Soûr, Lebanon), the Banû ‘Uqail, and of Tripoli (mod. Trâblous, Lebanon), the Banû ‘Ammār.In 1081 Tutush seized Tortosa (mod. Tartûs, Syria) from the Fātimids, weakening further the Fātimid naval presence in Syria.
With most of the Palestinian coast under Tutush’s control, the Fātimids allied with the ‘Uqailids of Aleppo, who refused to submit to Tutush’s authority. In June 1083 Damascus came under siege from the Aleppan army, which was defeated by Tutush. The Fātimid-Aleppan alliance caused Tutush to change his strategy by seeking good relations with the Fātimids of Egypt, although his diplomatic initiatives proved fruitless. In 1086 Sultan Malik Shāh arrived in northern Syria and appointed some of his Turkish commanders as governors in key cities there: Yāghī Siyān at Antioch (mod. Antakya, Turkey) and Aq-Sunqur at Aleppo. As they answered to Malik Shāh in Persia, Tutush’s authority and ambition in Syria were restricted. The Fātimids continued to press him in Palestine, capturing Sidon, Tyre, and Acre (mod. ‘Akko, Israel).
On the death of Malik Shāh (December 1092), Tutush decided to claim the sultanate, challenging the dead sultan’s sons Mahmûd (the designated heir) and Barkyāruq. He secured the support of all the Turkish leaders of Syria (including Aq-Sunqur) and was about to confront his nephew Barkyāruq in battle at al-Rayy in summer 1093, when Aq-Sunqur and another commander, Buzān, shifted their loyalties to Barkyāruq, forcing Tutush to retire to Damascus. Tutush spent the winter of 1093-1094 in Damascus and in the spring attacked Aleppo, having arranged a marriage between his son Ridwānand a daughter of Yāghī Siyān of Antioch. In May 1094 he defeated the Aleppan army and had Aq-Sunqur executed. By January 1095 Tutush had gained recognition as sultan from the Abbāsid caliph, and controlled most of Syria, Anatolia, Iraq, and western Persia. However, on 26 February 1095 his forces were defeated by the army of Barkyāruq in a battle at the village of Dashlu, south of the Caspian Sea, where Tutush was killed. He left five sons; two of them, Duqâq and Ridwân, started a civil war in Syria that continued up to the arrival of the First Crusade (1096-1099).