I want to know the answer to the following question:
Which people arrived in the British Isles when the Roman Empire's power was diminishing?
All the background I'm provided with is that "In time, Anglo-Saxon demands on the British became so great that they came to culturally dominate the bulk of southern Great Britain, though recent genetic evidence suggests Britons still formed the bulk of the population.". Is that enough to answer the question?
Answer: no