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?

full_context: Document 1: Battle of Stamford Bridge: The Battle of Stamford Bridge took place at the village of Stamford Bridge, East Riding of Yorkshire, in England on 25 September 1066, between an English army under King Harold Godwinson and an invading Norwegian force led by King Harald Hardrada and the English king's brother Tostig Godwinson. After a bloody battle, both Hardrada and Tostig along with most of the Norwegians were killed. Although Harold Godwinson repelled the Norwegian invaders, his army was defeated by the Normans at Hastings less than three weeks later. The battle has traditionally been presented as symbolising the end of the Viking Age, although major Scandinavian campaigns in Britain and Ireland occurred in the following decades, such as those of King Sweyn Estrithson of Denmark in 1069–1070 and King Magnus Barefoot of Norway in 1098 and 1102–1103.
Document 2: Ealdgyth, daughter of Earl Ælfgar: Ealdgyth ("fl. c". 1057–1066), also Aldgyth or in modern English, Edith, was a daughter of Ælfgar, Earl of Mercia, the wife of Gruffudd ap Llywelyn (d. 1063), ruler of all Wales, and later the wife and queen consort of Harold Godwineson, king of England in 1066. She was described by William of Jumièges as a considerable beauty.
Document 3: Sigtryg Eysteinsson: Sigtryg Eysteinsson was king of the Norwegian petty kingdoms Raumarike and Hedmark in what is today south-eastern Norway. He was killed by Halfdan the Black ("Halvdan Svarte") in the middle of the 9th century. Halfdan the Black subdued the area by first defeating and killing Sigtryg in battle and then defeated Sigtryg's brother and successor Eystein Eysteinsson in a series of battles.
Document 4: Earl of Northumbria: Earl of Northumbria was a title in the Anglo-Danish, late Anglo-Saxon, and early Anglo-Norman period in England. The earldom of Northumbria was the successor of the earldom of Bamburgh. In the seventh century, the Anglo-Saxon kingdoms of Bernicia and Deira were united in the kingdom of Northumbria, but this was destroyed by the Vikings in 867. Southern Northumbria, the former Deira, then became the Viking kingdom of York, while English earls ruled the former northern kingdom of Bernicia from their base at Bamburgh. The northern part of Bernicia was lost to the Scots, probably in the late tenth century. In 1006 Uhtred the Bold was earl of Bamburgh, and Æthelred the Unready appointed him earl of York as well, re-uniting the area of Northumbria still under English control into a single earldom. Uhtred was murdered in 1016, and Cnut then appointed Eric of Hlathir earl of Northumbria at York, but Uhtred's dynasty held onto Bernicia until 1041, when the earldom was again united. A descendant of Uhtred, Gospatric, was appointed earl by William the Conqueror in 1067, but William expelled him in 1072. Gospatric was then given lands in Scotland, and his descendants became earls of Dunbar. The earldom of Northumbria was broken up in the early Norman period and dissolved into the earldoms of York and Northumberland, with much land going to the prince-bishopric of Durham.
Document 5: Halfdan Ragnarsson: Halfdan Ragnarsson (Old Norse: "Hálfdan" ; or "Healfdene"; Old Irish: "Albann" ; died 877) was a Viking leader and a commander of the Great Heathen Army which invaded the Anglo-Saxon kingdoms of England, starting in 865. According to the tradition recorded in the Norse sagas he was one of the sons of Ragnar Lodbrok, and his brothers included Björn Ironside, Ivar the Boneless, Sigurd Snake-in-the-Eye and Ubba. He was the first Viking King of Northumbria and a pretender to the throne of Kingdom of Dublin. He died at the Battle of Strangford Lough in 877 trying to press his Irish claim.
Document 6: Ancestry of the Godwins: Very little is known for certain of the ancestry of the Godwins, the family of the last Anglo-Saxon King of England, Harold II. When King Edward the Confessor died in January 1066 his closest relative was his great-nephew, Edgar the Ætheling, but he was young and lacked powerful supporters. Harold was the head of the most powerful family in England and Edward's brother-in-law, and he became king. In September 1066 Harold defeated and killed King Harald Hardrada of Norway at the Battle of Stamford Bridge, and Harold was himself defeated and killed the following month by William the Conqueror at the Battle of Hastings.
Document 7: Ivar the Boneless: Ivar the Boneless (Old Norse: "Ívarr hinn Beinlausi" ; ) was a Viking leader and a commander who invaded what is now England. According to the "Tale of Ragnar Lodbrok", he was the son of Ragnar Lodbrok and Aslaug. His brothers included Björn Ironside, Halfdan Ragnarsson, Hvitserk, Sigurd Snake-in-the-Eye and Ubba.
Document 8: Cadfan ap Cadwaladr: Cadfan ap Cadwaladr, Lord of Ceredigion (c. 1140 - c. 1215) was the elder son of Cadwaladr ap Gruffydd, the brother of Owain Gwynedd, King of Gwynedd and overlord of all Wales. His mother was his father's first wife, Gwerfel ferch Gwrgan. He was probably born in Ceredigion, where his father held extensive estates. His father was banished in 1144. He should not be confused with Cadell ap Gruffydd, King of Deheubarth, who took Ceredigion from Hywel ab Owain Gwynedd, son of Owain Gwynedd, in 1150. Cadfan probably spent the rest of his life in exile in England. He married Gwenllian, a daughter of Owain Cyfeiliog. He is known to have had only one daughter: Tangwystl ferch Cadfan (born c. 1212).
Document 9: Rhiryd ap Bleddyn: Rhiryd ap Bleddyn (1049–1088) was a Welsh king of Powys. He was a son of Bleddyn ap Cynfyn and Haer verch Cillin.
Document 10: Owain ap Dyfnwal (died 1015): Owain ap Dyfnwal (died 1015) may have been an eleventh-century ruler of the Kingdom of Strathclyde. He seems to have been a son of Dyfnwal ab Owain, King of Strathclyde, and may well have succeeded Dyfnwal's son, Máel Coluim, King of Strathclyde. During Owain's reign, he would have faced a massive invasion by Æthelræd II, King of the English. Owain's death is recorded in 1015, and seems to have been succeeded by Owain Foel, a man who may have been his nephew.
Document 11: Bleddyn ap Cynfyn: Bleddyn ap Cynfyn (Old Welsh: "Bledẏnt uab Kẏnỽẏn" ;   1073), sometimes spelled Blethyn, was an 11th-century Welsh king. He was installed by Harold and Tostig Godwinson as king of Gwynedd in 1063 on his father's death, during their destruction of the kingdom of Bleddyn's half-brother, Gruffydd ap Llywelyn. He became king of Powys on his brother Rhiwallon's death in 1069. His descendants continued to rule Powys as the House of Mathrafal.
Document 12: Rhiwallon ap Cynfyn: Rhiwallon ap Cynfyn (c. 1020 – c. 1069 ) was a Welsh King. the son of Cynfyn ap Gwerstan and brother of King Bleddyn of Powys. Through his mother Angharad, he was half-brother to King Gruffydd ap Llywelyn as well. 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".
Document 13: Tostig Godwinson: Tostig Godwinson ( 1026 – 25 September 1066) was an Anglo-Saxon Earl of Northumbria and brother of King Harold Godwinson. After being exiled by his brother, Tostig supported the Norwegian king Harald Hardrada's invasion of England, and was killed at the Battle of Stamford Bridge.
Document 14: Rhirid Flaidd: Rhirid Flaidd (sometimes called Rhirid ap Gwrgenau) (fl. 1160), according to Welsh tradition, was the son of Gwrgenau, who is supported by an obscure and doubtful pedigree going back to Cunedda Wledig, the progenitor of the House of Cunedda which had provided the kings of Gwynedd from the end of Roman Britain until 825. The appellation of "blaidd" (wolf) was inherited from his maternal grandmother, Haer, daughter and heiress of Cynfyn, son of Cillyn y Blaidd Rhudd (meaning "Cillyn the Bloody Wolf") of Gest in Eifionydd. He was related through his grandmother to Bleddyn ap Cynfyn, king of Powys who rewarded Gwrgenau with land, presumably for his loyalty and service.
Document 15: Cynfyn ap Gwersytan: Cynfyn ap Gwerystan (born c. 990) — sometimes spelled Kynvyn, Kynwyn, Cynvyn, or Kynfyn — was a Welsh nobleman, principally known on account of his son Bleddyn ap Cynfyn, who established the House of Mathrafal over Powys as a consequence of a Saxon invasion in 1063.
ground_truth: Northumbria