He first appears on the record in 1018, when he defeated and killed Aeddan ap Blegywryd and his four sons, subsequently obtaining control of Gwynedd and Powys.
A battle ensued at Abergwili in 1022, where after significant casualties on both sides, Rhain was killed and Llywelyn took control of Deheubarth.
[2][3] According to the Brut y Tywysogion, Llywelyn's reign was prosperous, and he was dubbed "King of the Britons" by the Annals of Ulster.
[3] Llywelyn died in 1023, and despite his accomplishments, his son Gruffydd did not immediately succeed him, potentially due to his young age.
[4] Gruffydd would eventually become the first and only ruler to govern the entirety of what is now known as Wales, although he was killed by his own men in 1063.