Rhiwallon ap Cynfyn was a Welsh prince, the son of Cynfyn ap Gwerstan

Cynfyn ap Gwerstan

Cynfyn ap Gwerstan , also known as Cynfyn of Powys, was a royal figure in the Kingdom of Powys.He married Angharad, daughter of Maredudd ab Owain.He was the father of Rhiwallon ap Cynfyn and Bleddyn ap Cynfyn.-References:...

. On the downfall of Gruffydd ap Llywelyn

Gruffydd ap Llywelyn

Gruffydd ap Llywelyn was the ruler of all Wales from 1055 until his death, the only Welsh monarch able to make this boast...

 in 1063 he received (with his brother Bleddyn ap Cynfyn

Bleddyn ap Cynfyn

Bleddyn ap Cynfyn was a Prince of the Welsh Kingdoms of Gwynedd and of Powys.- Lineage :Bleddyn was the son of Princess Angharad ferch Maredudd with her second husband Cynfyn ap Gwerstan, a Powys Lord, about whom little is now known...

) North Wales on condition of faithfully serving Edward the Confessor

Edward the Confessor

Edward the Confessor also known as St. Edward the Confessor , son of Æthelred the Unready and Emma of Normandy, was one of the last Anglo-Saxon kings of England and is usually regarded as the last king of the House of Wessex, ruling from 1042 to 1066....

 ‘everywhere by water and by land.’ As the son of Angharad

Angharad

Angharad is a popular Welsh name, having a long association with Welsh royalty, history and myth. It translates to .-Mythology:Angharad, also sometimes known as Angharad Golden-Hand, is the lover of Peredur in the Welsh myth cycle The Mabinogion. In some versions of the story, Peredur meets her...

, daughter of Maredudd ab Owain ap Hywel Dda, he was Gruffydd's half-brother. In August 1067 he and Bleddyn joined Eadric the Wild

Eadric the Wild

Eadric the Wild , also known as Eadric Cild, was an Anglo-Saxon magnate of the West Midlands who led English resistance to the Norman Conquest, active in 1068-70.-Background:...

 in an attack upon Herefordshire

Herefordshire

Herefordshire is a historic and ceremonial county in the West Midlands region of England. For Eurostat purposes it is a NUTS 3 region and is one of three counties that comprise the "Herefordshire, Worcestershire and Gloucestershire" NUTS 2 region. It also forms a unitary district known as the...

, which was part of the general resistance to the Conqueror. In 1069 or 1070 the two fought the battle of Battle of Mechain

Battle of Mechain

The Battle of Mechain was fought in 1069 in Powys, Wales, for rule of the Welsh kingdoms of Gwynedd and Powys.After the murder of Gruffydd ap Llywelyn, Harold Godwinson married his widow Ealdgyth and divided Gruffydd's realm into the traditional kingdoms of Gwynedd and Powys, the rule of which were...

 with Maredudd and Idwal

Idwal

Idwal is Welsh for Lord of the wall and may refer to:*Cwm Idwal, a hanging valley in the Glyderau range of mountains in northern Snowdonia, Wales*Iago ab Idwal ap Meurig , a Prince of Gwynedd...

, sons of Gruffydd ap Llywelyn. Though they were victorious, Rhiwallon fell, leaving Bleddyn sole prince of North Wales. His daughter Nest married Rhys ap Tewdwr

Rhys ap Tewdwr

Rhys ap Tewdwr was a Prince of Deheubarth in south-west Wales and member of the Dinefwr dynasty, a branch descended from Rhodri the Great...

, and was mother of Nest who was the mistress of Henry I of England

Henry I of England

Henry I was the fourth son of William I of England. He succeeded his elder brother William II as King of England in 1100 and defeated his eldest brother, Robert Curthose, to become Duke of Normandy in 1106...

.