But this next period, the Rashidun, or the rightly guided caliphs, caliph means successors, essentially successors to Muhammad. Under these four caliphs, you see Islam spread from as far west as Tunisia and Egypt all the way through Persia. And keep in mind, this is spreading, overtaking, conquering what used to be controlled by very powerful empires, the Byzantine Empire or Eastern Roman Empire, taking territory from them here, and then Sassanid Persia, taking territory from them, and this is less than 30 years. And then it spreads even more. During the next caliphate, which is now dynastic, the Umayyad Caliphate, by the end of the 13th century, the Umayyad Caliphate, by the end of that, at 750 CE, you see Islam has now spread or conquered from modern day Spain and Portugal all the way to modern day India and Pakistan. And we could continue this narrative, and we will continue to talk about it in future videos, but what's really interesting is to think about how and why it was able to spread this rapidly. There's very few instances in history where we see this type of an empire form this quickly.