Question: Who was the brother of Tostig Godwinson that overthrew Gruffydd, Rhiwallon, and Bleddyn?
Sentence (from "Rhiwallon ap Cynfyn"): Following the 1063 invasion of Wales by Harold and Tostig Godwinson that overthrew Gruffydd, Rhiwallon and Bleddyn jointly received Powys and Gwynedd on condition of faithfully serving Edward the Confessor "everywhere by water and by land".
Relevant evidence: Yes