Why were Gauls no longer considered barbarians in the 5th century?

Since the time of Caesar, that is, more than four centuries, the Gauls lived within the Roman Empire, so that by the 5th century they adopted the urban culture, Latin letters, etc.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.