One of the Medieval kingdoms of Wales that briefly flourished in the twelfth and thirteenth centuries; its location roughly corresponding with that of modern shire county of Montgomery.
Kings of Powys Wenwynwyn
Part of the kingdom of Powys until 1160, then;
Annexed by Gwynedd between 1216 and 1240
Annexed by Gwynedd once more between 1274 and 1277, and by England thereafter.
Following the death of Madog ap Maredudd, king of Powys, his son Llywelyn ap Madog inherited northern Powys (known as Powys Fadog whilst his brother Gruffudd ap Maredudd gained southern Powys, which is generally known under the name Powys Wenwynwyn (1). (Although strictly speaking the appellation Wenwynwyn was only used to describe southern Powys from the reign of Gwenwynwyn onwards.)
Gwenwynwyn ap Owain sought to establish himself as a leader of the Welsh but his defeat at the Battle of Painscastle in 1198 effectively ended these ambitions after which he came under pressure from the expansionist Gwynedd on his north-eastern border. Hence from his point of view (and later that of his son), Gwynedd was a greater threat than the Norman kings of England. As demonstrated when in 1216 Gwenwynwyn was driven out of Powys Wenwynwyn by Llywelyn Fawr of Gwynedd and his son Gruffydd ap Gwenwynwyn had to wait until Llywelyn Fawr died in 1240 to recover his inheritance.
When Llywelyn ap Gruffydd later sought to once again expand the influence of Gwynedd, Gruffydd planned to have Llywelyn assassinated, but when the latter discovered the plot, he invaded Powys Wenwynwyn and Gruffydd fled into exile in England.
Which is why you later find the family of Gruffydd supporting Edward I in his struggle against Gwynedd in the years 1276 to 1282. With the final defeat and death of Llywelyn ap Gruffydd in 1282, Gruffydd ap Gwenwynwyn returned to power in his former lands, only this time not as king but as lord of Powys with his former kingdom now a marcher lordship. After Gruffydd's death in 1289, he was succeeded by his son Owain, who adopted the suitably Norman surname of de la Pole (2) as more befitting his place in the Cambro-Norman nobility.
(1) Quite probably a piece of opportunism on the part of Gruffydd ap Maredudd; taking advantage of the death of his brother to grab himself a kingdom
(2)de la Pole literally "of Pool", that is Welshpool, being the principal town of the area.
Pieced together from information in A History of Wales by John Davies (Allen Lane 1993) and the Powys County Archives online at http://archives.powys.gov.uk/