We hear a lot about this in Chinese history and also in contemporary Afghanistan, but instead of being called feudal lords, these landlords are called warlords. Eurocentrism striking again. The other reason the Dark Ages are called dark is because Europe was dominated by superstition and by boring religious debates about, like, how many angels can fit on the head of a pin. And while there's something to that, the Middle Ages also saw theologians like Thomas Aquinas, who was quite an important philosopher, and women like Hildegard of Bingen, who wrote all this important liturgical music and also basically invented the genre of the morality play. All that noted, things were certainly brighter in the Islamic world, or dar al-Islam. So when we last left the Muslims, they had expanded out of their homeland in Arabia and conquered the rich Egyptian provinces of the Byzantines and the entire Sasanian Empire, all in the space of about a hundred years. The Umayyad Dynasty then expanded the empire west to Spain and moved the capital to Damascus because it was closer to the action empire-wise, but still technically in Arabia.