There is mention of a kingdom called Mercia. That was one of the rooms in Highclere Castle/Downton Abbey on that British TV drama.
Mercia was one of the Heptarchy, the seven kingdoms that made up the Anglo-Saxon-Jute (and Viking) realm that became England. The others were Wessex (which became the backbone and unifier), Sussex, Kent (the Jutish kdm), Northumbria (Kingdom of York), Essex, and East Anglia, which went Viking thanks to conquest.
Ireland, Scotland, Wales, and Cornwall also had sets of small kingdoms, separate from England, with Viking presence and/or domination here and there.
English unification began with Alfred the Great (who may have reached the point of being the ancestor of everyone with English origins), who struggled with the Vikings until he’d beaten them, and brought Mercia into alliance (Mercia had suffered from the Viking predation).
His hmm, great-grandson I guess, Aethelstan, consolidated his rule and comprehensively defeated an alliance of adversaries from Viking Ireland, Scotland, Strathclyde, and York (the Welsh sat it out). He took his time, had good field intel, and made sure he had his army in the right place at the right time to face them piecemeal, before all of them arrived.
https://en.wikipedia.org//wiki/%C3%86thelstan#King_of_the_English
https://en.wikipedia.org/wiki/Battle_of_Brunanburh
In Search of Athelstan - In Search of the Dark Ages 19 March 1981
mrFalconlem
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January 18, 2014
Resynced and remixed from best available sources.
https://www.youtube.com/watch?v=zGL89IJYpO4