Sis for stealing the crown jewels of Armenia, and after several months of confinement, he was poisoned and killed. Zabel decided to embrace a monastic life in the city of Seleucia, but she was later forced to marry Constantine's son Het'um in 1226. Het'um became co-ruler as King Het'um I. The Het'umid dynasty By the 11th century the Het‘umids had settled into western Cilicia, primarily in the highlands of the Taurus Mountains. Their two great dynastic castles were Lampron and Papeŕōn/Baberon, which commanded strategic roads to the Cilician Gates and to Tarsus. The apparent unification in marriage of the two main dynasties of Cilicia, Rubenid and Het'umid, ended a century of dynastic and territorial rivalry, while bringing the Het'umids to the forefront of political dominance in Cilician Armenia. Although the accession of Het'um I in 1226 marked the beginning of Cilician Armenia's united dynastic kingdom, the Armenians were confronted by many challenges from abroad. In order to enact revenge for his son's death, Bohemond sought an alliance with Seljuk sultan Kayqubad I, who captured regions west of Seleucia. Het'um also struck coins with his figure on one side, and with the name of the sultan on the other. Armeno-Mongol alliance and Mamluk threat During the rule of Zabel and Het'um, the Mongols under Genghis Khan and his successor Ögedei Khan rapidly expanded from Central Asia and reached the Middle East, conquering Mesopotamia and Syria in their advance towards Egypt. On June 26, 1243, they secured a decisive victory at Köse Dağ against the Seljuk Turks. The Mongol conquest was disastrous for Greater Armenia, but not Cilicia, as Het'um preemptively chose to cooperate with the Mongols. He sent his brother Smbat to the Mongol court of Karakorum in 1247 to negotiate an alliance. He returned in 1250 with an agreement guaranteeing the integrity of Cilicia, as well as the promise of Mongol aid to recapture forts seized by the Seljuks. Despite his sometimes-burdensome military commitments to the Mongols, Het’um had the financial resources and political autonomy to build new and impressive fortifications, such as the castle at Tamrut. In 1253, Het'um himself visited the new Mongol ruler Möngke Khan at Karakorum. He was received with great honors and promised freedom from taxation of the Armenian churches and monasteries located in Mongol territory. Both during his trip to the Mongol court and in his 1256 return to Cilicia, he passed through Greater