I am presently researching the political climate and wars of mid to late 9th Century Britain and Ireland, and was curious to find that King Rhodri of Gwynedd is regularly named "The King of the Britons". My sources unfortunately have yet to delve deeper into the politics of Wales in this era, but it left me curious: If Rhodri sat upon the throne of Gwynedd, presumably at Aberffraw on the Isle of Anglesey, would not his rein have extended - at its most extreme - to the geographic area around Welshpool?
If indeed he were "King of the Britons", would not he have had to have been at least the king of Wales entirely? Why was he given such a grandeur and all encompassing title?
Thank you!
Obviously the first thing you've hit on here is that "the Britons" i.e. the Britonnic/Brythonic people is a different matter from "the people of Britain", i.e. the modern state, and that we're looking at a scenario where the Britons mostly occupy Wales, Cornwall, and some sites in modern-day Spain and France. They've been pushed westwards gradually by the Saxons and Danes and are still fending them off.
Rhodri's title "King of the Britons" comes from the Annals of Ulster, which was compiled in 1489 out of earlier sets of annals. He's also noted in there as fleeing to Ireland in 877 from "dark foreigners" who are probably the Danes, and in 878 as being killed by the Saxons. In the Chronicon Scotorum, which has a frustratingly loose provenance, the translation I checked referred to him as King of Wales, but I suspect this is a either an anachronism or a mistranslation.
He (or his extended family) probably controlled a large portion of Wales by the time of his death, and the Fragmentary Annals of Ireland also refer to his son Cadell's son Hywel Dda i.e. Howel the Good as "King of the Britons". We can be more certain from the better legal sources that Hywel Dda controlled a large part of Wales, and even made a pilgrimage to Rome (at least, according to the Chronicle of the Princes). Looking at the charters he signs, he moves from styling himself as subregulus/undercyning to regulus and rex after the death of his cousin Idwal in 943, even while he's still kind of subordinate to Eadred, which I think is the key here.
So what seems to be happening is that Rhodri is being - essentially - given an "overkingship" of the Britons by the Irish Annals. This may or may not reflect what's actually happening on the ground (and may even be about how Rhodri was representing himself to the Irish), but implies that even if he doesn't rule everywhere where the Britons live, he still has authority and some level of control over those places.