Much of what people associate with the idea of a medieval Arab caliphate is rooted in the reign of our upcoming caliph. The foundation he laid for his dynasty is so solid that it makes the Umayyad era seem like little more than a formalized extension of the early Arab raids against their neighboring empires. It will take us a while to get through his reign, and before we start with that, we’ll take this episode to better orient ourselves within the world he is about to reshape.