The Mongols werent Muslim, or at least until very late in history! They were in fact friendlier to Christians than Muslims and the Crusaders used cheered the Mongols on against the Muslims of Egypt as a last resort of maintaining their hold on Levant against Egypt. During the Sack of Baghdad in 1258, the Mongols were allowed to kill rape assault all they want against Muslims, but Christians were spared, seen as local allies.

In SS, the Mongol thing is completely off. When Martok (or Monk, i get confused between these two) played as the mongols in SS 6.1, he jihaded against the christians. He posted his screenies at pics and history of your empire thread. That is TOTALLY off. If i made that mod, i might have still let them be muslim, but they wont be able to build anything religious structures and units, join jihads, but their religious unrest would be eliminated or drastically cut, as they were tolerant to all religions. Chingis Khan himself approved all religions but didnt believed anyone of them is completely right.