Toghrul III was the last sultan of the Great Seljuk Empire and the last Seljuk Sultan of Iraq. His great uncle Sultan Ghiyath ad-Din Mas'ud had appointed Shams ad-Din Eldiguz as atabeg of his nephew Arslan-Shah, the son of his brother Toghrul II, and transferred Arran to his nephew's possession as iqta in 1136. Eldiguz eventually married Mu’mina Khatun, the widow of Toghril II, and his sons Nusrat al-Din Muhammad Pahlavan and Qizil Arslan Uthman were thus half-brothers of Arslan Shah, but despite close ties with the Royal Seljuk house, Eldiguz had remain aloof of the royal politics, concentrating on repelling the Georgians and consolidating his power. In 1160, Sultan Suleiman-Shah named Arslan Shah his heir and gave him governorship of Arran and Azerbaijan, fearful of the power of Eldiguz.

The Seljuk Empire, or the Great Seljuk Empire, was a high medieval, culturally Turco-Persian, Sunni Muslim empire, established and ruled by the Qïnïq branch of Oghuz Turks. It spanned a total area of 3.9 million square kilometres from 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.