Question: Rhiwallon ap Cynfyn, was a Welsh King, following the 1063 invasion of Wales by Harold and Tostig Godwinson, he was an Anglo-Saxon Earl of which location, that overthrew Gruffydd, Rhiwallon and Bleddyn jointly?
Sentence (from "Ælfgar, Earl of Mercia"): He succeeded to his father's title and responsibilities on the latter's death in 1057.
Relevant evidence: No