 A second mission sent in 1245 by Pope Innocent was led by the Dominican Ascelin of Lombardia , who met with the Mongol commander Baiju near the Caspian Sea in 1247 . Baiju , who had plans to capture Baghdad , welcomed the possibility of an alliance and sent a message to Rome via his envoys Aïbeg and Serkis . They then returned a year later with Pope Innocent 's letter , Viam agnoscere veritatis , in which he appealed to the Mongols to " cease their menaces " . 
