The Eastern Roman Empire fell because of a mix of problems. One problem was the fact that there were many different groups fighting each other, including the Byzantine (Roman) Empire, the Turks, and the Mongols. Additionally, the Byzantine economy was weak and couldn't support a strong government or military. This made it difficult for them to resist invaders. Lastly, the Byzantine Empire was facing a lot of corruption from its leaders, meaning that the people in charge weren't doing their jobs properly and the empire was having trouble staying organized. All of these factors combined caused the Eastern Roman Empire to collapse.