List four reasons for the fall of the western Roman empire?

The term the fall of Rome refers to the fall of the western part of the Roman Empire. This was a process which took several decades. The process was determined by more than three factors. It was precipitated by the invasions by the Germanic peoples (the Vandals, the Sueves) and the Alans (who were Iranian speakers) who invaded the empire and took over north-western Africa and part of Spain, the Alemanni who took over Switzerland and northwester France and the Burgundians who settled in east France The loss of the agricultural rich territory in Africa lead to a significant loss in revenue for the Roman government. The Visigoths, another Germanic people, who had been allowed to settle in the eastern part of the Roman Empire and then moved to south-western France,took advantage of the situation to take over Hispania (Spain and Portugal). The Romans lost political unity. There were usurpations and infighting which made it difficult to respond to the invasions effectively. There was also a failure by the combined fleet of the western and eastern part of the Roman Empire to dislodge the Vandals from Africa. It ended in disaster and was very costly. The Romans army became reliant on Germanic soldiers and two Germanic commanders-in chief of the Roman army and installed puppet emperors (three by Ricimer, one by Gundobad and one by Orestes.Amidst this political instability, the reign of the last emperors was short.