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?
Facts:
Tostig Godwinson is an Anglo-Saxon Earl of Northumbria
Tostig Godwinson overthrew Gruffydd, Bleddyn, and Rhiwallon
Answer: Northumbria