I mean, as yet another barbarian group falling upon a weakened Mediterranean. Works that compare the Arian Goth and Muslim Arab regimes would be great.
Primary, secondary, and even historiographic texts would be welcome.
Hugh Kennedy has a good book called [The Great Arab Conquests] (http://www.amazon.co.uk/The-Great-Arab-Conquests-Changed/dp/0753823896/ref=sr_1_5?ie=UTF8&qid=1398602714&sr=8-5&keywords=the+arab+conquests) which is an overview of the initial conquests. He does a good job at looking at the primary sources, from the Byzantines and the Sassanids, as well as later secondary sources from the Arab writers.