Perhaps in the knowledge that many of the Mongols were Christian, but not knowing how much the Mongols detested and feared exposure to the remains of the dead, Christian priests attempted to keep the Mongols out of Pest by parading the bones and other relics of their saints before the approaching army. The exposure to pieces of dead bodies enraged the Mongols, for whom such acts were ritually contaminating as well as disgusting. The fearful and angry Mongols not only slew the clerics, but burned the relics and the churches as well to purify themselves from the pollution.
