Yes, those impregnable fortresses from which the Assassins terrorised the local Moslems for years. Hulegu and his ox bows destroyed them and rather quickly. People keep stating lack of pasture as if the Mongol army would grind to a halt without it. They were quite capable of conducting seiges, they did so throughout China and they were more capable than most at adapting. Attila marched his army as far as Orleans and the Huns were never really numerous why would the Mongol army struggle where the Huns had not?

......Orda