Nizam al-Mulk, c.1018-92, vizier (1063-92) under two Seljuk (see Turks) sultans. Of Persian descent, he was early educated in administration, serving the Ghaznavids sultans. By 1059 he was chief administrator of Khorasan; in 1063 the Seljuks made him their vizier. Nizam al-Mulk remained in that position throughout the reigns of Alp Arslan and Malikshah. His power peaked under the latter, when he wrote the extensive treatise entitled Siyasat-nameh, or "Book of Government." A devout Sunni Muslim, Nizam al-Mulk also founded a number of theological schools. He was assassinated in 1092.