Seisyllwg (Welsh: [sɛiˈsəɬʊɡ]) was a petty kingdom of medieval Wales. It is unclear when it emerged as a distinct unit, but according to later sources...

Deheubarth was united around 920 by Hywel Dda out of the territories of Seisyllwg and Dyfed, which had come into his possession. Later on, the Kingdom of...

and eventually came to rule most of Wales. He became the sole king of Seisyllwg in 920 and shortly thereafter established Deheubarth, and proceeded to...

of Wales) Seisyllwg, a petty kingdom from 680 to 920, comprising Ceredigion and Ystrad Tywi. In 871, Princess Angharad inherited Seisyllwg, and her husband...

most important being Gwynedd, Powys, Deheubarth (originally Ceredigion, Seisyllwg and Dyfed) and Morgannwg (Glywysing and Gwent). Boundary changes and the...

Merfyn. Angharad was the daughter of Meurig, who was evidently the King of Seisyllwg in southwestern Wales. She was a descendant of Cunedda through his son...

 870/871) was a 9th-century king of Ceredigion and Ystrad Tywi (i.e., Seisyllwg) in southwest Wales. Gwgon was the son of the former king Meurig ap Dyfnwallon...

Dyfed Ergyng Glywysing Gwent Gwynedd Morgannwg Powys Rhwng Gwy a Hafren Seisyllwg Dumnonia Ancient Cornwall (legendary) Dukes Mann Mann & the Isles Mann...

Cadell ap Rhodri (854–909) was King of Seisyllwg, a minor kingdom in southwestern Wales, from about 872 until his death. Cadell was the second son of...

Deheubarth out of his maternal and paternal inheritances of Dyfed and Seisyllwg in 930, ousted the Aberffraw dynasty from Gwynedd and Powys and then codified...