How is the end of Roman rule in Britain best explained?

The End of Roman rule in Britain was a gradual process which occurred from 383 to 410 AD whereby the Western Roman Empire ultimately decided to evacuate Roman Britain, which had been subjected to various Celtic and Germanic invasions and was tying down large numbers of Roman Army legionaries needed to protect the crumblnig Western Empire's European and North African provinces. The end of Roman rule was quickly followed by the emergence of Romano-British kingdoms and their eventual conquest by the same Germanic mercenaries whom the Romans had imported to fight off the Celts.

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