Who conquered the roman west empire

As fighting in the border regions decentralized the empire, competing armies fought to thrive their generals selected as emperor. The results were devastating to the economy, administration, and morale of the empire. Rome could no longer win its frontier battles against invaders. The rise of Christianity also took away from the power of Roman Emperors except for Constantine who supported it. Climate change and disease also led to the fall of Rome.

The theory is land mass basically what they said.