Read up on the Mongol invasions, and particularly their conquest of Baghdad (the capital of the then ruling Abassid Khilafat). They slaughtered scholars en mass

Read up on the Mongol invasions, and particularly their conquest of Baghdad (the capital of the then ruling Abassid Khilafat). They slaughtered scholars en masses, and dumped so many books into the Tigris that it's said that the river turned black (from ink), not red. Baghdad is smaller today than it was then. Just to show how much of an impact was felt.