the Tran accepted Mongol overlordship, and Uriyangkhadai withdrew. The Vietnamese king Trần Thái Tông paid tribute to Uriyangkhadai who had quickly evacuated Vietnam to escape malaria. The Trần dynasty accepted terms of vassalage and sent tributes to the administration of Möngke. To strengthen his control over Tibet, Möngke made Qoridai commander of the Mongol and Han troops in Tibet in 1251. In 1252–53 Qoridai invaded Tibet, reaching as far as Damxung. The Central Tibetan monasteries submitted to the Mongols, and the Mongol princes divided them as their appanages. Conflicts with the Delhi Sultanate In 1252–53 Sali Noyan of the Tatar clan was sent to the Indian borderlands at the head of fresh troops and was given authority over the Qara'unas. Sali himself was subordinate to Möngke's brother Hulagu. Due to the internal conflicts of the Delhi Sultanate, the Mamluk Sultan Nasiruddin Mahmud's brother, Jalal al-Din Masud, fled into Mongol territory in 1248. When Möngke was crowned as Khagan, Jalal al-Din Masud attended the ceremony and asked help from Möngke, who ordered Sali to assist him to recover his ancestral realm. Sali made successive attacks on Multan and Lahore. Sham al-Din Muhammad Kart, the client malik of Herat, accompanied the Mongols. Jalal al-Din was installed as client ruler of Lahore, Kujah, and Sodra. In 1254 the Delhi official Kushlu Khan offered his submission to Möngke Khan and accepted a Mongol darughachi. When he failed to take Delhi, Kushlu turned to Hulagu. In the winter of 1257–58 Sali Noyan entered Sind in strength and dismantled the fortifications of Multan; his forces may also have invested the island fortress of Bakhkar on the Indus. Conquest of the Middle East When Möngke called a kurultai to prepare the next conquest in 1252/53, the Sultanate of Rum and the Lu'lu'id dynasty of Mosul were subject to the Mongol Empire. The Ayyubid ruler of Mayyafariqin, Malik Kamil, and his cousin in Aleppo and future Sultan, Malik Nasir Yusuf, sent envoys to Möngke Khan, who imposed darughachis (overseers) and a census on the Diyarbakır area. Möngke followed the schemes of his predecessor against the Nizari Ismailis (Assassins). Möngke's decision to launch a campaign against Nizari castles followed anti-Nizari urges by Sunnis in the Mongol court, new anti-Nizari complaints (including Shams-ud-Din, the chief judge of Qazvin), and warnings from local Mongol commanders in Persia. In 1252, Möngke entrusted the mission of conquering the rest of Western Asia to