One cause for Romes fall was that the Barbarians conquered Rome.
Never Never NEVER
Another reason why Romes fell down was that after 476 ce there was no Roman emperor and without an emperor who will rule Rome and that could have made people do nasty things like murdering and stealing.
There is another reason why Rome fell down.This is because during 235ce to 284ce there were 41 emperors.Imagine 40 other people competing with you for a leadership spot.
There were selfish emperors who only cared about themselves