Within the Pictish king lists a mid-7th century king Talorgan son of Eanfrith appears. Prior to this there are a few clear Brythonic and Irish interpolations in the lists, such as the two Gartnaits (likely a Pictish form of the name Arthur), and Nechtan grandson of Uerb (Neithon map Guipno of Alt Clut). This clear interpolation of a Germanic name is striking, and interestingly a chain of events that started with the battle of Catraeth likely led to this unique political arrangement.
The Anglian kingdom of Deira seemed to initially operate as a foederati state of the Coeling hegemony which was first based from Ebrauc (Modern York) and eventually moving west under Urien of Rheged’s overlordship, while early Bernicia seemed to have been a foederati state of another northern Brythonic hegemony based around Alt Clut. Neither of these kingdoms have Germanic names, they are instead of Brythonic origin, Deifr, and Bryneich. The survival of these names indicates that Brythonic maintained some relevance even to the early Anglian settlers, which would naturally be a result of a longstanding client relationship between these larger Northern coalitions and their foederati settlements.