When dealing with muawiyah it is always best to be somewhat skeptical. I can’t say there were no Breton fighting in Spain, but I really doubt there were many if any at all. Just an example of what I am talking about: muawiyah says there this:
“(NOTE: Bieber ~ as in Rodrigo Díaz de Vivar ~ AKA El Cid!)”
The problem is that Vivar probably has nothing to do with the Breton. If it is Celtic, it probably has everything to do with Spain’s own ancient Celtic population which pre-dated any Breton on the continent by centuries:
The Celtic Vaccaei were living in the Vivar region many centuries before El Cid. http://en.wikipedia.org/wiki/Vaccaei
You already know that but for some unknown reason you want to sugar coat the Islamic invasion and conquest of Iberia.
When it was over the Christians were reduced to those living North of the mountains along the coast of the Bay of Biscay.
They never recovered sufficiently to mount any sort of military offensive against the Muslims ~ that came from outside, from elsewhere in Europe.
Modern Christian Spain began with Leon and Castile ~ a fairly informative but very brief brief is at http://en.wikipedia.org/wiki/Kingdom_of_Castile ~ you did notice I didn't refer to San Cho Noe I, but they do refer to Sancho II and Sancho III ~ they came later ~ MUCH LATER.
The Reconquista was in full sway by Sancho III. Galician chronicles demonstrate it began with arrivals from Cornwall ~ and by necessary implication, Brittany.
That's the Galician story. The movement of the Milesians to Brittany took place in the aftermath of the climate anomaly in roughly 535AD ~ they took their Arthurian stories with them which included the chronicles of the British kings ~ in pre Anglo-Saxon times.
Ergo, the Celtic population in Brittany circa 7th Century-9th Century (and so on up to today) was essentially the same as the Celtic population in Ireland, Wales, Britain and Cornwall from roughly 700BC up until modern times ~ there is a short brief at http://en.wikipedia.org/wiki/Kingdom_of_Castile which you might want to review to pick up on the words.
here is a basic differentiation in the two main threads called Goedelic and Brethonic to deal with, and if you want to start reading old Breton language texts, they had about 7 standard ways of spelling so you need to get over that.
Now, your alternate history is the Celts in Brittany are DIFFERENT FROM the Celts in Galicia?
'you'll need to 'splain that one!
Thanks for your responses and for supplying a different point of view and alternative explanations for some of the things mentioned.