We have the Byzantine Empire continuing to lose territory. Remember, in the seventh century, as Islam expanded out of Arabia, it quickly overran much of the territory in the Holy Land that at the time was controlled by the Byzantines, Byzantine being another word for the Eastern Roman Empire. By the time of this map, Islam had been in control of the Middle East, the Holy Land, North Africa, and even a good chunk of the Iberian Peninsula for several hundred years, as much as over 400 years. As we get closer to this time period, you have the Seljuk Turks continuing to eat in to the Byzantine Empire and taking most of the Anatolian Peninsula. Also at this time, remember, we are in the High Middle Ages, which is a time when especially Western Europe is on the rise. There's increased agricultural productivity. The population is increasing.