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?
{'answer': 'Northumbria', 'supporting_facts': [['Rhiwallon ap Cynfyn', 3], ['Tostig Godwinson', 0]]}