I'm looking for book recommendations regarding the early caliphates. In particular, I am interested in learning more about what underlay their phenomenal rapid expansion against the Sassanids, Byzantines, and Western Roman successor kingdoms, among others. What was it about their military, administration, economy, etc that underlay their successes?
I minored in history but consider myself a layperson, so a book in the middle with regards to complexity would be appreciated. Examples of books I found very readable include Justinian's Flea and 1491. "India: A History" was at the upper edge of readability for me.
Thanks in advance!
For a general overview of early Islam and its conquests, Robert Hoyland's In God's Path: The Arab Conquests and the Creation of an Islamic Empire (2014) is your best bet. Another good introduction is the chapter from the New Cambridge History of Islam (2010), especially if you can access it from a university library. For a detailed analysis of military issues, check out Hugh Kennedy's The Armies of the Caliphs: Military and Society in the Early Islamic State (2001). If you are more interested in the social/political side of things, his The Prophet and the Age of the Caliphates (2004) is excellent as well. These books are all very recent and readable, especially Hoyland's (it was written for a popular audience), so you will be getting the very latest in scholarship and hopefully have an enjoyable time as well :)