During the Middle Ages in Europe, several empires rose and fell, the most prominent being the Holy Roman Empire, which dominated Central Europe. The Byzantine Empire, centered in Constantinople, preserved classical knowledge and provided a buffer against external invasions. Meanwhile, the Islamic Caliphates expanded across Europe, Africa, and Asia, fostering cultural exchanges and advancements in science, medicine, and philosophy. The Feudal System characterized the socio-economic structure, leading to the rise of regional powers and the decline of centralized authority. Over time, empires like the Mongol Empire also briefly dominated vast territories, showcasing the dynamic and often tumultuous nature of medieval European history.