Perfeddwlad or Y Berfeddwlad was the name during the 12th century for the territories in Wales lying between the River Conwy and the River Dee. In the early Middle Ages, the region was known as Tegeingl, after the Celtic tribe Deceangli which inhabited the region since the 1st century BC. This region is also known as Gwynedd Is Conwy, or Lower Gwynedd; in contrast with Gwynedd Uwch Conwy, or Upper Gwynedd. The region was composed of the cantrefi of Rhos, Rhufoniog, Dyffryn Clwyd and Tegeingl. As the rivalries between Gwynedd, Powys, and England evolved in the High Middle Ages, the region became known in Welsh as the Y Berfeddwlad, the middle country, as it was situated between upper Gwynedd in the west, England to the east, and Powys to the south. Shortly after the death of Owain, the ruling Prince of Gwynedd, his son and heir Hywel was ousted in a coup lead by his stepmother; he was replaced by his step-brothers Rhodri, Maelgwn, and Dafydd, who ruled jointly. However, within a year, the ruling brothers fell into dispute, forcing Maelgwn to flee to Ireland, while Dafydd and Rhodri eventually divided Gwynedd between them; Angelsey and the Perfeddwlad went to Dafydd. In 1194, Llywelyn Fawr, the senior heir of Owain Gwynedd, defeated Dafydd in the Battle of Aberconwy, and took over the Perfeddwlad. Following Rhodri's death the following year, Gruffudd, another grandson of Owain Gwynedd by yet another son, took over the remainder of Gwynedd; when Gruffudd died in 1200, Llywelyn inherited these lands as well. Llywelyn's expansionist conflicts with Reginald de Braose, William Marshal, and Powys Wenwynwyn, lead to his dominance of Wales, but following his death, his brother-in-law, King Henry III of England, temporarily invaded the Perfeddwlad in order to force Llywelyn's son - Dafydd - to agree to limit his authority to Gwynedd. Henry took Dafydd's bastard elder brother Gruffydd hostage to ensure compliance. Following Gruffydd's accidental death a few years later, Dafydd forged an anti-English alliance against his uncle, resulting in a pre-emptive English invasion, in 1245. Dafydd died without heirs the next year, but the war was continued by Gruffydd's sons until 1247, when they decided to make peace with the King - the Treaty of Woodstock. The Treaty gave Henry the Perfeddwlad, which he gave to his own son, while the rest of Gwynedd was divided between Gruffydd's two adult sons. After a decade, the population of the Perfeddwlad felt that their grievances were not being adequately addressed by Edward, and appealed to Llywelyn for assistance. Llywelyn was himself already aggrieved that when Llywelyn's younger brother, Dafydd, had reached adulthood, Henry had promised to re-divide Gwynedd so that Dafydd would also have lands to rule. So it was that in late 1256 Llywelyn invaded the Perfeddwlad, and captured it. Supply-line problems led to a series of defeats for the English, who subsequently had to abandon their campaign to deal with serious conflicts between the King and his Barons. In 1269, the King's weakened authority over the whole kingdom, and Llywelyn's gains in the meantime, lead to the Treaty of Montgomery, by which Henry acknowledged Llywelyn's gain of the Perfeddwlad, and his dominance over the rest of Wales - acknowledging Llywelyn as Prince of Wales. However, when Llywelyn married Eleanor de Montfort, the daughter of Henry's greatest enemy, Edward - now king of England - demanded an explanation, in person. Llywelyn refused to attend, insisting he wouldn't be safe, so Edward declared him a rebel, and in 1277 attacked Gwynedd with an enormous army, seeking to depose Llywelyn entirely. Once Edward captured the Perfeddwlad and Angelsey, Llywelyn sought a peace agreement, resulting in the Treaty of Aberconwy:
the Perfeddwlad was divided between Edward and Llywelyn's brother, Dafydd
Llywelyn was permitted to rule the remainder of Gwynedd, Angelsey being restored to him
the title Prince of Wales, however, was reduced simply to a label, no longer conferring any authority - all lesser rulers in Wales were released from any obligation to Llywelyn
Edward had kept the coastal Cantrefs of the Perfeddwlad, while Dafydd gained Rhufoniog and Dyffryn Clwyd. Nevertheless, by the end of 1281, the Welsh princes who had supported Edward had become disillusioned, and in early 1282 Dafydd attacked the English castles of Hawarden and Rhuddlan, instigating sympathetic outbreaks of anti-English violence in the rest of wales. Llywelyn decided to support his brother. Edward's reaction was fierce, the revolt was crushed, Llywelyn was killed in battle, and Dafydd was caught, tried by Edward's parliament, and hung, drawn, and quartered. Gwynedd was abolished, its relics and assets taken to Westminster, and Dafydd's sons were imprisoned for life. Following the consequent Statute of Rhuddlan, in 1284,
