There are sections of Islamic History which mention Hasan-i-Sabbah briefly but no writer treats the subject in details. Hodgson and Lewis published under a misleading title of Assassinsand more recently F. Daftary wrote a general history of the Ismailis. Thus there is a need of a book covering the topic in greater depth and details.Hasan Sabbah; His life and thought, covers the history of the Middle East Crusade Period. It also deals with the founder of the Nizari Ismaili State in the North Iran and Syria and against the powerful Seljuks and the Sunni Caliphate of Islam.