Kings settlement, Aberffraw cantref

The emergence of the Kings of Gwynedd permanently in the Aberffraw district (cantref), Wikipedia links used.

After the original division of Kingdoms in sub-Roman Britain, Wales was further divided into what was called the 'Cantrefi' (similar to townships). Then within the cantref were 'commotes' (cymwt in middle Welsh) which were a further land division.

Image courtesy of Wikimedia Commons, attributed to XrysD through Wiki Commons, Welsh cantrefi map. 

The Kingdom of Gwynedd's (Guynet) cadet branch was in the Aberffraw cantref on the Isle of Anglesey, North Wales. The dynasty was named the House of Aberffraw and it would align itself with Gwynedd and its rulers, they had held successive royal titles from different locations at the same time. Those titles could be of King or Prince of Gwynedd, or of Aberffraw, also Lord of Eryri (Snowdon) or Anglesey as well as temporary vassal lordships south of Gwynedd in Ceredigion and Meirionnydd (Merionethshire). This style of multiple royal titles is similar to the current Prince of Wales, William, he's styled with different titles, such as Dukedoms, e.g. Cornwall or Rothesay, as well as multiple Baron and Earl titles amongst others.

It wasn't until the 9th century that the House of Aberffraw officially emerged in Wales. However, the permanent settlement of the Kings of Gwynedd in the Aberffraw cantref (county division) was recorded in the early 7th century. A royal family's presence was the next wave of rulers since the Roman Empire's control of Anglesey. This time, the rulers of Gwynedd established themselves near the now village of Aberffraw. After the repelling of Irish Celts in the 5th century, the Kings of Gwynedd (Cadwallon Lawhir) built a palace at Aberffraw and they became the authoritative figures in Anglesey. The presence of Kings on Anglesey coincided with the founding of Christianity in the British Isles and the beginnings of the Church in Wales. The first mentions of Churches in Gwynedd involved the foundation of religious places of worship as part of a nationwide bishopric. Saint Deniol (Daniel, c. 6th century) became the first Bishop of Bangor (episcopal area of North-west Wales), a position still occupied today over 1,500 years later. On Anglesey, was the union between King and Church in St Cadwaladr's Church, part of the former Aberffraw cantref. This connection has been cemented over a millennium later with the presence of the tombstone of Cadfan ap Iago in the church.

Image courtesy of Wiki Commons, attributed to Richard Keatinge. Catamanus Stone, St. Cadwaladr. 

Image courtesy of Wiki Commons, attributed to Rhion, Catamanus stone enhanced image. 

The 'Catamanus stone' (634 AD) reads in Latin: Catamanus rex sapientisimus opinatisimus omnium regum. 

Translated to English: King Cadfan, the Wisest and Most Renowned of All Kings (Google Translate: King Catamanus was thought to be the wisest of all kings).

King Cadfan was the son of Iago, King of Gwynedd, and 3x great-grandson of Cadwallon (grandson of Cunedda) who first allied himself with the local Welsh Celts battling against fellow Celts, the Irish Picts who invaded Anglesey. The Kings of Gwynedd permanently settled the area on the south-west of the Isle of Anglesey to help the local tribes against foreign invaders as descendants of fellow Welsh Ordovices Celts. Between the emergence of the royal family in the Anglesey cantrefs and their eventual settlement as the Aberffraw dynasty, there was also the establishment of other royal courts (llys in Welsh). Maelgwn Gwynedd, a 6th-century King of Gwynedd held court in Deganwy castle. Then his son Rhun Hir ap Maelgwn, one of the Three Fettered War-Bands (Welsh triads, Wiki source), and a contemporary of King Arthur (Mabinogion: The Dream of Rhonawby) had established his stronghold against the Saxon English at Caerhun (Canovium), the previously inhabited Roman fort on the then-only road between Chester and Caernarfon. Within the Kingdoms of Wales, the Cantrefi were sub-divisions of land and they were all ruled by their respective capitals. In the Aberffraw cantref, the village of Aberffraw was named the capital (principal and preferred family seat). And of all the Welsh Kingdoms, the location was considered to be the Kings' favourite royal court (llys) in comparison to other contemporary royal residences.

Image courtesy of Wiki Commons, attributed to Notuncurious. The Kingdom of Gwynedd map circa 620.

The ancestors of Cadfan were British Kings and had settled in Gwynedd, Wales as part of the final Royal family dynasty titled the King of Britain, a title which began circa 1,000 BC. Cadwaladr ap Cadwallon, also known as Cadwaladr the blessed (Welsh: Fendigaid) was his grandson, became a Christian monk, and retired to a monastery in the Aberffraw cantref. On a trip (pilgrimage) to Rome in 664 he died, his body was brought a thousand miles to Gwynedd and buried in the church which bears his name today. Cadwaladr was also remembered by Henry Tudor (VII of England) who claimed descent from Cadwaladr in the 22nd degree (generations). He was the first person to raise the Red Dragon flag, a flag incorporated into the current flag of Wales. Henry flew the banner at the Battle of Bosworth during the conclusion of the War of Roses in 1485. 

Image courtesy of Wiki Commons, attributed to Llywelyn2000. Flag of Cadwaladr (Llandaff Cathedral). 

The Kingdom would maintain a close relationship with the Church and the Kings' descendants would become Saints and leaders of the Christian faithful in Wales. The permanent settlement of Aberffraw was set in stone for most of the medieval ages and the royal house's monarchs were recognised for their rule not only in Anglesey, nor Gwynedd, or even Wales but all of Britain.