Prior to the First Council of Lyon in March 1245, Innocent IV dispatched four embassies to the Mongols, one of which included Ascelin.
He was accompanied by Simon of St Quentin, who wrote the account of the mission in his Historia Tartarorum; two unknown men, Alberic and Alexander; and the Dominican friar Guichard of Cremone, who had already been stationed for 5 years in Tiflis.
He did not bring gifts to the Mongols, and refused to show them respect by genuflection unless they would accept baptism, thereby angering them to a considerable extent.
[1] The princes invited Ascelin to travel further east with them to meet the Great Khan in Karakorum, Mongolia, but he declined the offer.
[3] In response, the pope issued the papal bull Viam agnoscere veritatis, which appealed to the Mongols that they should stop killing Christians.