I think the crusades weren't as bad for Islamic development as we like to believe. The Mongol invasions which happened around the time of the last serious Crusa

I think the crusades weren't as bad for Islamic development as we like to believe. The Mongol invasions which happened around the time of the last serious Crusades in the Middle East probably did more lasting damage. The cultured Islamic states were basically conquered by nomadic pagan hordes, while at the same time being battered by the crusades. For instance, look at the sack of Baghdad by Genghis Khan - a major center of science and learning at that time. Eventually the nomads - Mongols and Turkic tribes - eventually settled down and converted, but a lot was lost and the focus on discovery and science never reached the same level again. (Note: this is not historical revisionism where I'm trying to minimize the evil that were the crusades. I'm not saying the crusades weren't really really bad, they were. I'm just saying the Muslims were capable of repelling the Christian invasions and retake lost territories without being damaged beyond repair. At the same time, a lot of those who fell to Mongol expansion were wiped of the map for good or reduced to tributary kingdoms.)