André de Longjumeau (also known as Andrew of Longjumeau in English) was a 13th-century Dominican missionary and diplomat and one of the most active Occidental diplomats in the East in the 13th century. He led two embassies to the Mongols: the first carried letters from Pope Innocent IV and the second bore gifts and letters from Louis IX of France to Güyük Khan. Well acquainted with the Middle-East, he spoke Arabic and "Chaldean" (thought to be either Syriac or Persian). Mission for the holy Crown of Thorns André's first mission to the East was when he was asked by the French king Louis IX to go to Constantinople to obtain the Crown of Thorns which had been sold to him by the Latin Emperor Baldwin II in 1238, who was anxious to obtain support for his empire. André was accompanied on this mission by a Dominican friar, brother Jacques. Papal mission to the Mongols (1245–1247) André of Longjumeau led one of four missions dispatched to the Mongols by Pope Innocent IV. He left Lyon in the spring of 1245 for the Levant. He visited Muslim principalities in Syria and representatives of the Nestorian and Jacobite churches in Persia, finally delivering the papal correspondence to a Mongol general near Tabriz. In Tabriz, André de Longjumeau met with a monk from the Far East, named Simeon Rabban Ata, who had been put in charge by the Khan of protecting the Christians in the Middle-East. Second mission to the Mongols (1249–1251) At the Mongol camp near Kars, André had met a certain David, who in December 1248 appeared at the court of King Louis IX of France in Cyprus. André, who was now with the French King, interpreted David's, a real or pretended offer of alliance from the Mongol general Eljigidei, and a proposal of a joint attack upon the Islamic powers of Syria. In reply to this the French sovereign dispatched André as his ambassador to Güyük Khan. Longjumeau went with his brother Jacques (also a Dominican) and several others – John Goderiche, John of Carcassonne, Herbert "Le Sommelier", Gerbert of Sens, Robert (a clerk), a certain William, and an unnamed clerk of Poissy. The party set out on 16 February 1249, with letters from King Louis and the papal legate, and rich presents, including a chapel-tent lined with scarlet cloth and embroidered with sacred pictures. From Cyprus they went to the