And this was, to some degree, the case under Justinian, and it was very clear at this time that the Byzantine emperor was very powerful, not just over the temporal realm, really referring to the day-to-day material realm, but also a lot of influence on the spiritual realm, which was really supposed to be the domain of the bishops or the popes or the patriarchs. This notion of the pentarchy was codified in the Justinian law, this idea that these five centers of Christianity really have extra weight and collectively are really leading Christendom. Now, as I mentioned, things get interesting as we fast forward about 250 years. So let's go to the year 800. So one thing you might notice is that group in yellow, the Franks, have now conquered a lot more, and they're conquering it under the leadership of Charlemagne. At the same time, you see this green over here. Islam has dramatically spread from its founding in the early 7th century all the way now as we're exiting the 8th century to cover most of the Middle East, Persia, bordering on modern-day Pakistan, India, North Africa, and even going into modern-day Spain.