Problem is this is one of those "things" the Moslems don't want anybody else to talk about. They don't discuss it themselves.
Recent Christian scholarship, independent of Arab records on the matter, indicates that Islam as an independent religion simply did not appear until long after the Conquest and the establishment of the Arabian Empire.
Probably took that long to Islamicize the Arabs themselves ~
It appears to be a total fabrication that the imperative behind the Conquest was a religion ~ rather, it's simply a case of the bad boys in Mecca escaping the Dark Ages first. They prettied up their history later on when they realized their pagan past was an embarrassment.
Doggone it, where you guys been? The whole thing is "FAKE".
the Eastern Empire didn't have a "dark ages"