Roman \"Abandonment\" of Britain: Fact or Fiction?

[Agraes]

Gohar, king of the Alans, was sent to Armorica. Brittany didn't exist by yet, the name only appears in the 6th century. Territories settled by the Britons on the continent were perhaps called Letavia by then
Armorica isn't only Brittany, it was much larger, including a good part of western Gaul between Loire and Seine. There is a lot of misconceptions about this.

Jordanes when he wrote about the Catalaunian fields list Britons (or Letavi depending of the manuscripts) and Armoricans among the allies of Aetius, ie germanic foederati in Gaul, saying all of those use to be soldiers of Rome but now served her as auxiliaries (something we may take with the meaning of Foederati).

Britons - those in the west - were technically roman citizens but had much more to do with gentiles and foederati. A romanised and christian elite, a dual culture, but barbarian laws and language.
In Brittany the difference was clear between "Romans" ie Armorican/romano-gallic population and the Britons in the early medieval period, just like elsewhere in Gaul.

And it's not unlikely Riothamus (sometimes adequated with Ambrosius Aurelianus) was himself coming from Dumnonia or Durotrigia, lands that preserved or revived a somewhat warlike culture without need to ask saxon federates to settle down and take the power