One glaring problem here...the latter Mongol hordes *were* Muslims.
Most especially one can look at Tamerlane who could fairly be called a fanatical Islamic "crusader".
Tamerlane, more properly Timur Lenk, or Timur the Lame was indeed Muslim, having adopted the religion to make his rule a bit more acceptable to the Muslim states he subjugated in central asia.
Timur was essentially a terrorist as he would ruthlessly exterminate entire cities, ususally allowing a very fuew to live, maimed and sent off to nearby settlements to spread the fear. But he never made much attempt to hold territory or to rule it. It's hard to fathom what drove the man, but you have to conclude that he was a bloody minded maniac for starters.
The earlier, and far more successful, Mongols (Genghis Khan and his sons, for example) were by and large animists or Buddhists.
A really good book about these people is "Warriors of the Steppes" - can't remember the author's name...
? The Mongols conquered much of Islam and the Ottoman Empire, and some of them may have been 'absorbed' into the Islamic cult, but the the Huns and Moslems were at war against each other. The Huns (Mongols) conquered and reconqured Baghdad and Persia, but it was an Egyptian army commanded by Marmeluke Sultan Kutuz who won the first victory against the Mongols.