The correct answer is - Two once mighty empires were collapsing because of internal strife and foreign invasions.
The Byzantine Empire managed to outlive Rome by approximately 1,000 years, but the way in which both, the Eastern and the Western Empire ended is pretty much the same.
Both Rome and Byzantine were very large empires, but as they were nearing their end, they were gradually losing their territories until the only remaining part of the empire was the most important city and the closest area around it.
The fall of these two empires was because of internal strife, where the aristocracy was only concerned about their personal interest and wealth, while totally forgetting the country, but also because of the multiple strong military forces that emerged on the scene and weakened them.
