Malik-Shah was born on 16 August 1055 and spent his youth in Isfahan. According to the 12th-century Persianhistorian Muhammad bin Ali Rawandi, Malik-Shah had fair skin, was tall and somewhat bulky. In 1064, Malik-Shah, only 9 years old by then, along with Nizam al-Mulk, the Persian vizier of the Empire, took part in Alp Arslan’s campaign in the Caucasus. The same year, Malik-Shah was married to Terken Khatun, the daughter of the Karakhanid khan Ibrahim Tamghach-Khan. In 1066, Alp Arslan arranged a ceremony near Merv, where he appointed Malik-Shah as his heir and also granted him Isfahan as a fief.
In 1071, Malik-Shah took part in the Syrian campaign of his father, and stayed in Aleppo when his father fought the Byzantine emperor Romanos IV Diogenes at Manzikert. In 1072, Malik-Shah and Nizam al-Mulk accompanied Alp-Arslan during his campaign in Transoxiana against the Karakhanids. However, Alp-Arslan was badly wounded during his expedition, and Malik-Shah shortly took over the army. Alp-Arslan died some days later, and Malik-Shah was declared as the new sultan of the empire.
After Alp Arslan’s assasination in 1072, Maliq Shah (shown in picture: below left)became the new Seljuk sultan but spent some of his years in defeating his uncle Qawurd, who had been trying to become the sultan. After this revolt was put down and Qawurt killed, Malik Shah marched on the rebellious Qarakhanids and Gaznawids to ensure the Seljuk rule. Both vassals were defeated and forced to make peace. He moved the Seljuk capital from Ray to Isfahan and also organised three campaigns against Georgia and advanced as far as the Black Sea.
The Seljuk Empire now stretched from the shores of Mediterrenean up to the Central Asian mountains to the East. Armenians, Georgians, Abbasids, Qarakhanids and Gaznawids were now the vassals of the Seljuk sultans. Nizam Al Mulq, a Sunni Persian, was a great administrator, who stayed as the Seljuk Grand Vizier during both Alp Arslan’s and Maliq Shah’s reign. He was later assasianted by Hassan Sabbah’s Shi’a Assasins. Nizam Al Mulq is credited with being the re-organiser of the Iqta military system (similar to the Byzantine Theme and Sui Chinese Fu systems); he was also the founder of the famous Nizamiyah Madrasah (Muslim University) in Baghdad