I was today years old when I knew that the first Christian crusade was over 400 years after the muslim conquests began. I researched the dates to confirm. What I found was a bit different but similar ballpark. The Siege of Damascus was stated to be in 634 (vs 635) and the first Crusade was in 1096 (vs 1059). Either way, the muslim conquests had been going on for 462 years before there was any Christian response. Kind of makes you see things a little differently. The world would try to shame us for the Crusades. I think 462 years is long enough to give them the benefit of the doubt.