The decline of the Roman Empire was a gradual process that occurred over several centuries, culminating in the fall of the Western Roman Empire in 476 AD. Factors contributing to this decline included economic troubles, military defeats, and political instability. The empire faced invasions from various groups, such as the Visigoths and Vandals, which weakened its borders. Additionally, internal issues like corruption, a declining population, and reliance on mercenary forces further eroded the empire's strength. The division of the empire into the Western Roman Empire and the Eastern Roman Empire also played a role, as the eastern half became more prosperous and stable, while the west struggled to maintain control.