The domain of the Banu Munqidh entered a long period of stability and prosperity beginning in 1138 . Shayzar and it ’s dependencies remained under the control of Sultan who ruled under the authority of the Zengid dynasty . However , in 1140/41 the Ismai'ils captured the fortress of Masyaf from the Banu Munqidh , who had purchased it in 1127/28 . It thereafter became the Isma'ilis ' main stronghold in Syria . This generally peaceful period also coincided with tensions between Sultan and his nephews . Murshid 's position as the Banu Munqidh 's second highest-ranking leader enabled the latter 's sons , including Usama , to rise politically within the emirate . They gained a reputation for their martial and diplomatic skills and Sultan viewed their prominence as a threat to his leadership . These tensions culminated after Murshid 's death in 1136/37 and the birth of Sultan 's son Taj al-Mulk Muhammad in the following year . As a consequence , Usama and his brothers were exiled from Shayzar , finding asylum with Nur ad-Din , the Zengid emir of Aleppo . After Sultan 's death in 1154 , Taj al-Mulk Muhammad succeeded him without incident . Most of the Banu Munqidh , including Taj al-Mulk and his children , died in the collapse of the Shayzar citadel during the August 1157 earthquake , which devastated a number of other towns in the area . This brought an end to their rule of the Shayzar principality , which was soon after seized by Nur ad-Din to prevent its capture by the Crusaders . Nur ad-Din did not seek to find any surviving members of the Banu Munqidh to resume their lordship of Shayzar , whose fortifications he had promptly restored . Instead , he handed the town over to a certain Sabiq al-Din Uthman ibn al-Daya . The latter 's family , the Banu al-Daya , remained the lords of Shayzar through Ayyubid rule until 1233
August 1157 earthquake
1157 Hama earthquake
Banu Munqidh