Right? The conclusion is quite suspect because the Mongols eventually did conquer southern China where it is perpetually warm and humid. What they ended up doin

Right? The conclusion is quite suspect because the Mongols eventually did conquer southern China where it is perpetually warm and humid. What they ended up doing was solidifying their control of northern China and then adopting infantry based tactics and riverine warfare in addition to adopting trebuchets from the Middle East/Europeans. The Mongols were quite adaptable. I doubt warmer weather would be enough to stop them on its own.