What effect did barbarian invasions have on the Western Roman Empire?

One effect did barbarian invasions have on the Western Roman Empire was that they weakened Roman law and government.

Explanation:

The weakening of Rome gave rise to Barbarian and also initiated the beginning of the Middle Ages. Rome was the epicenter of food, trade, and military of Europe. In spite of being one of the largest Empires in the world at that time, it was among the few monarchies to have trade with military support. Its downfall shatters the prosperous trade system of Western Europe.

The lust for supremacy triggered a civil war among the emperors of the Roman Kingdom that effected the administration and competence of the army. The war for power inside the Roman Empire also affected the economy and increased the risk of foreign invasion.

The Barbarin took advantage of the administrative incompetence of the Roman empire and started their invasion along the Western part and initiated their annexation to establish their empire in the western domain. Their annexation proceeded as the boon for the further demise and weakening of the law and government of the Romans.

i would go with the last one

its many islands, high mountains, and remote peninsulas isolated population centers.