[1][2] They effectively replaced the House of Gwertherion, who had been ruling the Kingdom of Powys since late Roman Britain, through the politically advantageous marriage of an ancestor, Merfyn the Oppressor.

The House of Mathrafal's influence was greatest between 1063 and 1081, until they lost control of Gwynedd to a resurgent Aberffraw family following the Battle of Mynydd Carn.

[12][13] Despite being crowned as Owain IV of Wales in 1404, and having taking control of all Wales, and having created the first Welsh parliament at Harlech Castle, they eventually lost the war to the English forces of Henry IV and Henry V.[13] Nonetheless, their efforts didn't go in vain, as their rebellion gave rise to the first Welsh Kings of England, the Royal House of Tudor.

[14] Glyndŵr was also the wealthiest Welshman in Wales before his downfall in 1415, and captured number of Longshanks's main castles such as Conwy, Harlech and Beaumaris, and besieged Caernarfon.

The House was succeeded by the descendants of prince Owain Glyndŵr and his brother, lord Tudur ap Gruffudd, through the Vaughans of Corsygedol in Snowdonia, North Wales.

[9] His father, Merfyn, had previously allied his family with the last rulers of Powys by marrying Princess Nest, the daughter or sister of King Cyngen.

[36][note 1] In Welsh tradition, her family was of the Royal House of Gwertherion, and had been ruling Powys since the 5th century, through the marriage of an ancestor, Vortigern, the High king, to Sevira, the daughter of the Roman Emperor, Magnus Maximus.

[39][40][41] Maximus, a relative of the Imperial Theodosian dynasty, is featured on the Pillar of Eliseg, erected in the lordship of Yale by king Cyngen of Powys (b.

[42][43][44] As a consequence of Merfyn's alliance, King Cyngen's legitimate heirs were either exiled or reduced to the level of minor land owners (e.g., the family of Sir Gruffudd Vychan).

Other noble families claimed descent from another of Cyngen's sons, Elisedd, who is mentioned as killing his older brother Gruffydd in the Annales Cambriae.

[6] It is possible, however, that Powys remained independent until its 916 annexation by Cadell's son Hywel Dda, who also conquered Dyfed and Gwynedd and established what has become known as the realm of Deheubarth.