Islam caused the Dark Ages - The argument for it.

Pirenne

Emmet Scott revives an overlooked book by Pirenne to argue that Islam in effect caused the Dark Ages. The barbarians who had arrived earlier didn't try to erase the Greco-Roman culture, they had hung onto it.  On the emergence of militant Islam, the "Middle Sea" changed from a highway of trade to a battleground.  By the mid seventh century, luxury goods and the classical culture infrastructure disappeared around the Mediterranean.  Soil erosion (as farms were abandoned near the coast) and castles came into prominence and the Roman emperor stopped having his face on coinage after 640 AD.   This story runs against the prevailing wisdom but has supporting facts.  By the year 1000, it's true that Europeans were going to Islamic lands to acquire preserved knowledge but before that, Islam suppressed more than it preserved.  A detailed review of Emmet Scott's book, "Mohammed and Charlegmagne Revisited"  and  Amazon.com where a couple chapters can be freely read.