Final answer:
The division of the Roman Empire weakened the central government's ability to defend against invading tribes. Internal political problems, external threats, and strained resources further contributed to Rome's inability to stop the invaders.
Step-by-step explanation:
The division of the Roman Empire contributed to Rome's inability to stop invading tribes because it weakened the ability of the central government to defend the borders effectively. In the late fourth century CE, the western Roman Empire was faced with an increasing number of barbarian tribes that were better organized and capable of defeating large Roman forces. The division of the empire made it difficult for the Roman government to coordinate and respond effectively to these threats.
This division also led to internal political problems within Rome, such as the auctioning off of the throne by the Praetorian Guard and assassinations of rival emperors. Additionally, external factors, such as the rise of the aggressive Sassanids in Persia and the growing strength of barbarian groups along Rome's northern borders, further contributed to Rome's inability to stop invading tribes.
The continuous conflicts and the increasing size of the Roman military also strained the empire's resources and made it more difficult to defend against invading tribes. The distance from the central government in Rome and the cost of running far-flung military campaigns added to the challenges faced by the Roman Empire.