The date of the (beginning of the) construction by the Nizari Ismailis is variously given as 1097 (per ''
Jami' al-tawarikh), 1103 (per Zubdat al-Tawarikh), and during the Imamate of Ala al-Din Muhammad (1211–1255) (per Tarikh-i Jahangushay''). The fortress was on a great spur of rock rising almost vertically from the valley. Its ramparts were made of plaster and gravel. Elsewhere it has been described as an "extraordinary cave-fortress". On 19 November 1256, Khurshah with a group of notables left the fortress and surrendered to Hulagu Khan. Considering how well-fortified and well-provisioned Alamut was, the Mongols welcomed the surrender. Maymun-Diz was subsequently destroyed and its inhabitants were massacred. This is traditionally considered the date of the disestablishment of the
Nizari Ismaili state. ==See also==