Apart from having left a permanent stamp on the nomenclature of central Wales, Gwenwynwyn, during the first years of his career, made the boldest bid for Welsh political leadership ever undertaken by a prince of the royal house of Powys. He was not without the requisite courage and ambition, and a critical lull in the domestic fortunes of the royal families of Gwynedd and Deheubarth provided an opportunity for action. After a few easy successes, however, Gwenwynwyn fell victim to the forces which had recurrently in the past kept Powys from achieving anything more than a fleeting pre-eminence among the native dynasties of Wales.

Two attacks on marcher territory between the Wye and the Severn were disastrous for him, and on the second occasion, in 1208, he was deprived by king John of all his lands. Though restored by John in 1210, continuous pressure from Llywelyn the Great forced Gwenwynwyn, in 1212, to enter into that uneasy alliance with the prince of Gwynedd, which, continuing throughout the years of crisis in England, culminated with the oath of homage sworn by Gwenwynwyn to Llywelyn in 1215; but the breach of that oath in 1216, though Gwenwynwyn d. an exile later in that year, shows clearly how uneasy the new association was, and is ominous for the future relations of the two provinces. Gwenwynwyn was survived by two infant sons — Gruffydd ap Gwenwynwyn (q.v.) and Madog.