region later called İçel. At the end of the 13th century, these Turcomans established the Karamanids. The Ayyubids, who were disturbed by the rapid expansion of Sultan Kayqubad I, especially in eastern Anatolia, took action against the sultan under the leadership of Al-Kamil in Egypt. In 1234 Kayqubad I completely defeated the allied Ayyubid forces. Afterward, Harput expanded its borders further in the south-east Anatolia region by capturing Siverek, Urfa, Harran and Raqqa. The sultan defeated the Artuqids and the Ayyubids and absorbed the Mengujek emirate into the sultanate, capturing the fortresses of Hısn Mansur, Kahta, and Çemişgezek along his march. He also put down a revolt by the Empire of Trebizond and, although he fell short of capturing their capital, forced the Komnenos dynasty family to renew their pledges of vassalage. At first Kayqubad sought an alliance with his Turkish kinsman Jalal ad-Din Mingburni against the Mongol threat. The alliance could not be achieved, and afterwards Jalal ad-Din took the important fortress at Ahlat. Kayqubad finally defeated him at the Battle of Yassıçimen between Sivas and Erzincan in 1230. After his victory, he advanced further east, establishing Seljuq rule over Erzurum, Ahlat and the region of Lake Van (formerly part of Ayyubids). The Artuqids of Diyarbakır and the Ayyubids of Syria recognized his sovereignty. He also captured a number of fortresses in Georgia, whose queen sued for peace and gave her daughter Tamar in marriage to Kayqubad's son, Kaykhusraw II. Mindful of the increasing presence and power of the Mongols on the borders of the Sultanate of Rum, he strengthened the defenses and fortresses in his eastern provinces. He was given poison during a feast at Kayseri and died at an early age on 31 May 1237, the last of his line to die in independence. Historian Ibn Bibi mourned his death with these words,"With Kayqubad's death, the back of Islam was broken and the bond of kingdom and religion snapped". Succession Kayqubad had three sons: Kaykhusraw II, eldest son of his Greek wife Mah Pari Khatun, Rukn al-Din and Kilic Arslan, sons of his Ayyubid princess wife Malika Adila Khatun. According to Ibn Bibi, Kayqubad wanted Rukn al-Din as his successor who was the elder one of his two sons from his Ayyubid wife, Malika Adila Khatun, but Kaykhusraw usurped the throne and had Rukn al-Din, Kilic Arslan and their mother strangled. Architectural and cultural legacy Kayqubad sponsored