I am currently listing to a podcast on the history of Byzantium. Among the interesting and relevant parts are recent episodes that chronicle the rise of the Arab state and the swift conquering of Syria and Egypt from the Romans. Areas the Empire had held for centuries and whose loss led inexorably to the fall of Constantinople.
Among the topics covered are:
A discussion of what made for power in the region, it was whoever had the standing army in the field.
The tribalism and religious fractures that disaffected people from there governors, whose presence offered stability, and made them welcome new rulers despite the uncertain terms of the new rule.
The co-opting of the then still vague Mohamedian religion into medieval Islam by building a back story designed to legitimize and bless the military regime that wound up in control decades later.
History repeats itself because people, in aggregate are the same as we have always been.
It is enlightening to see how the same trends are playing out with ISIS.
I've long had an interest in Byzantine history (thanks to my interest in wargaming), and so followed the link.
In the context of your comments above about the 7th century collapse of Byzantine power in Egypt and Syria, I was about to recommend Tom Holland's "In the Shadow of the Sword" when I saw that one of the earlier episodes was an interview with Holland.
Oh well, I'll recommend the book anyway. Holland is a superb writer, and the points he makes in ITSOTS suggest a subtly different origin for Islam than I was familiar with. The key thing for me is that he doesn't speculate much. Instead the story he tells is firmly grounded in the work of (Western) academics relying on archaeological and textual evidence.
(And Holland's other books are fascinating reads too.)
