as Turkish soldiers who struck down Buri in 1131. The Assassins were hacked to pieces by Buri's guards, and he died of his wounds the following year. Mahmud II died in 1131 and his brother Ghiyath ad-Din Mas'ud (Mas'ud) was recognized as successor by Abbasid caliph al-Mustarshid. The succession was contested by Mahmud's son and other brothers, and al-Mustarshid was draw into the conflict. The caliph al-Mustarshid was taken prisoner by Seljuk forces in 1135 near Hamadan and pardoned with the proviso that he abdicate. Left in his tent studying the Quran, he was murdered by a large group of Assassins. Some suspected Mas'ud and even Ahmad Sanjar with complicity, but the chronicles of contemporaneous Arab historians ibn al-Athir and ibn al-Jawzi do not bear that out. The Isma'ilis commemorated the caliph's death with seven days and nights of celebration. The reign of Buzurg Ummid ended with his death in 1138, showing a relatively small list of assassinations. He was succeeded by his son Muhammad Buzurg Ummid, sometimes referred to as Kiya Muhammad. The Abbasids' celebration of the death of the Assassin leader Buzurg Ummid was short-lived. The son and successor of the last high-profile victim of the Assassins, al-Mustarshid, was ar-Rashid. Ar-Rashid was deposed by his uncle al-Muqtafi in 1136 and, while recovering from an illness in Isfahan, was murdered by Assassins. The addition of a second caliph to the Assassins' so-called "role of honor" of victims again resulted in a week of celebration at Alamut. Another significant success was the assassination of the son of Mahmud II, Da'ud, who ruled in Azerbaijan and Jibal. Da'ud was felled by four Assassins in Tabriz in 1143, rumored to have been dispatched by Zengi, atabeg of Mosul. The decades after the assassination of al-Mustarshid showed an expansion of Assassin castles in Jabal Bahrā', to the northwest of their Syrian fortresses in Jabal as-Summaq. In 1132, Saif al-Mulk ibn Amrun, emir of al-Kahf, recovered the fortress of al-Qadmus from the Franks, known to them as Bokabeis. He then sold the fortress to the Assassins in 1133. This was followed by the ceding of al-Kahf Castle itself to Assassin control in 1138 by Saif's son Musa in the midst of a succession struggle. These were followed by the acquisition of the castle at Masyaf in 1140 and of Qala'at al-Khawabi, known to the Crusaders as La Coible, in 1141. Relatively little is recorded