Little known truth: Islam was the cause of the Dark Ages. The amount of knowledge they destroyed with the libraries they burned set mankind back hundreds of years. These savages destroyed the idea of cause and effect, the basis of the scientific method. There was no natural law; only that of the Prophet who used a false religion to hide its only goal: conquest.
I’m not so sure about that one. The Roman Empire had already disintegrated before Islam was even really getting started and Europe was falling into a fragmentation of fiefdoms and unsafe travel.
I’m sure the invading hordes of islam didn’t help, but I think the dark ages was dark for many reasons.