Hulagu Khan's assumption of the title Ilkhan (subject khan) in 1256. Badr al-Din Lu'lu' died in July/August 1259, and his realm was divided between his sons, and Jazirat Ibn ʿUmar was bequeathed to his son al-Malik Al-Mujahid Sayf al-Din Ishaq. The sons of Badr al-Din Lu'lu' chafed under Mongol rule and soon all had rebelled and travelled to Egypt seeking military assistance as al-Muzaffar Ala al-Din Ali left Sinjar in 1260, al-Salih Rukn al-Din Ismail left Mosul in June 1261, and finally Ishaq fled Jazirat Ibn ʿUmar for Egypt shortly afterwards. Prior to his flight, Ishaq extorted 700 dinars from the city's Christians, and news of his impending escape pushed the populace to riot against his decision to leave the city to the wrath of the Mongols. In Ishaq's absence, 'Izz ad-Din 'Airbag, Emir of Amadiya, seized the city, and an attack by Abd Allah, Emir of Mayyafariqin, was repelled. Baibars, Sultan of Egypt, refused to provide an army to the sons of Badr al-Din against the Mongols, but they were permitted to accompany Caliph Al-Mustansir on his campaign to reconquer Baghdad from the Mongols. The three brothers marched with the caliph's campaign until they split at Al-Rahba, and travelled to Sinjar, where Ali and Ishaq briefly remained whilst Ismail continued onwards to Mosul. However, the two brothers abandoned Sinjar and Jazirat Ibn ʿUmar to the Mongols, and returned to Egypt upon learning of the caliph's death and defeat in November. Mosul was sacked and Ismail was killed by a Mongol army, after a siege from November to July/August 1262. After the sack of Mosul, the Mongol army led by Samdaghu besieged Jazirat Ibn ʿUmar until the summer of 1263; the siege was lifted and the city spared when the Church of the East bishop Henan Isho claimed to have knowledge of chrysopoeia, and offered to render his services. Jemal ad-Din Gulbag was appointed to govern Jazirat Ibn ʿUmar, but he was later executed for conspiring with the city's former ruler Ishaq, and was replaced by Henan Isho, who was also executed in 1268, following accusations of impropriety. In the second half of the 13th century, Mongol gold, silver, and copper coins were minted at Jazirat Ibn ʿUmar, and production there increased after Khan Ghazan's (r. 1295–1304) reforms. It was later attested that the vizier Rashid-al-Din Hamadani had planned to construct a canal from the Tigris by the city. Jazirat