What happened to the barbarian celts of the 5th century?

In the 5th century, they invaded the declining Roman Empire and they gradually carved it up the between them. 'The barbarians' never intended to destroy the Roman Empire, they wanted to share in its wealth but it was declining anyway and soon broke down altogether.

(Brainliest is appreciated :)

the answer would be c

these civilizations were located around fertile rivers, where they could produce an abundance of crops