Great question.... First off, Rome started in the year 753 BC and ended in the year 476 AD almost 1000 year rein over Europe... That being said plenty of barbarian invasion hurt the empire (The Hunnic Empire). Also political problems hurt the empire, many politicians and senators were fighting amongst them selfs and huge civil wars broke out during the late 3rd and 4th centuries... Finally, I would say Religion might have played a role in the empire collapse. Since Jesus died on the cross many have spread Christianity across the empire, which some say was the MAIN reason why Rome fell....
