Title: Seisyll ap Dyfnwal
Content:  Seisyll was the son of Dyfnwal ap Caradog ap Ynyr Fychan and his wife, said to have been Joyce daughter of Hamelin de Balun. He was a brother-in-law of Rhys ap Gruffydd, the Lord Rhys, King of Deheubarth. He held lands in present-day Monmouthshire, part of the old Welsh Kingdom of Gwent, and his main base was at Castell Arnallt, a motte and bailey style fortified site situated near the River Usk a few miles south of Abergavenny, near modern-day Llanover. It is today just a mound in a riverside field.
Title: Seisyll ap Dyfnwal
Content:  Seisyll ap Dyfnwal was a 12th-century Welsh Lord of Gwent Uwchcoed (Upper Gwent).
Title: Seisyll
Content: Kings Sisillius I and II, legendary kings of the Britons ; Seisyll ap Clydog (late 7th century), a king of Ceredigion ; Seisyll ap Rhun (10th century) ; Seisyll ap Ednywain or Owain, father of King Llywelyn of Gwynedd ; Seisyll ap Dyfnwal (12th century), a lord of Upper Gwent ; Seisyll Bryffwrch (12th century), a poet ; Seisyll ap Rhun Fychan (13th century) Seisyll or Seisyllt is a Welsh male given name. It may refer to: 
Title: Seisyll ap Dyfnwal
Content:  Seisyll ap Dyfnwal is best known for being an unwitting victim of the Norman Baron, William de Braose, 3rd Lord of Bramber, who had him murdered in cold blood on or very near Christmas Day 1175 at Abergavenny Castle. Seisyll, along with all the other Welsh princes and leaders from the area, was invited to Abergavenny Castle at Christmas by William De Braose on the understanding that they could voice grievances, overcome differences and plan a period of relative peace following a period of conflict. Some Welsh leaders stayed away, mistrusting de Braose. Seisyll attended along with his eldest son Geoffrey. Most other leaders followed suit and attended, assured of peaceful intent at the castle and surrendering their arms. Once inside the walls they were cut down without mercy by armed 
Title: Dyfnwal, King of Strathclyde
Content:  Dyfnwal (died 908×915) was King of Strathclyde. Although his parentage is unknown, he was probably a member of the Cumbrian dynasty that is recorded to have ruled the Kingdom of Strathclyde immediately before him. Dyfnwal is attested by only one source, a mediaeval chronicle that places his death between the years 908 and 915.
Title: Seisyll Bryffwrch
Content:  Seisyll Bryffwrch (fl. 1155-1175) was a Welsh-language poet. Seisyll competed against and was defeated by Cynddelw in a contest for the role of chief court poet to Madog ap Maredudd, prince of Powys. Seisyll's own compositions include elegies on the death of Owain Gwynedd and of Iorwerth Drwyndwn grandfather and father respectively of Llywelyn ab Iorwerth. Seisyll also wrote poems in praise of the campaigns of the Lord Rhys.
Title: Seisyllwg
Content:  Seisyllwg was a petty kingdom of medieval Wales. It is unclear when it emerged as a distinct unit, but according to later sources it consisted of the former Kingdom of Ceredigion plus the region known as Ystrad Tywi. Thus it covered the modern county of Ceredigion, part of Carmarthenshire, and the Gower Peninsula. It is evidently named after Seisyll, king of Ceredigion in the 7th or early 8th century, but it is unknown if he was directly responsible for its establishment. In the 10th century Seisyllwg became the centre of power for Hywel Dda, who came to rule most of Wales. In 920 Hywel merged Seisyllwg with the Kingdom of Dyfed to form the new kingdom of Deheubarth.
Title: Seisyll ap Clydog
Content:  Seisyll appears in the Harleian genealogies for the kings of Ceredigion. Here, he is named as the son of Clydog or Clitauc Artgloys, and is the sixth in descent from Ceredig, the traditional founder of Ceredigion. The Harleian also names him as the father of Arthgen, presumably the King of Ceredigion whom the Annales Cambriae record as dying in 807. Seisyll's name appears to derive from the notional Late Latin *Saxillus, which comes from the same root as the Welsh sais, meaning Saxon or Englishman. Seisyll ap Clydog is generally taken to be the Seisyll for whom Seisyllwg was named. As such, historians such as John Edward Lloyd and Egerton Phillimore believed that he was the king who founded that kingdom. However, contemporary sources continue to use the name Ceredigion for the realm of Seisyll and his successors. As such, "Seisyllwg" may represent a substantially later political development.
Title: Owain ap Dyfnwal (fl. 934)
Content:  far beyond the Clyde valley.  Owain was likely a son of Dyfnwal, King of Strathclyde. Dyfnwal is specifically attested by only one source, the ninth- to twelfth-century Chronicle of the Kings of Alba, which reveals he died between 908 and 915. Dyfnwal's parentage is unknown, although he might have been a member of the British dynasty that ruled Strathclyde before him. He could have been a son or grandson of Eochaid ap Rhun. Alternately, Dyfnwal could have represented a more distant branch of the same dynasty. In any case, the names borne by Owain and his apparent descendants suggest that he was indeed a member of the royal kindred of Strathclyde.
Title: Dyfnwal ab Owain
Content:  The names of the latter and of his apparent descendants suggest that they were indeed members of the royal kindred of Strathclyde. Sons of Dyfnwal seem to include Rhydderch, Máel Coluim, and Owain. The name of Dyfnwal's son Máel Coluim is Gaelic, and may be evidence of a marriage alliance between his family and the neighbouring royal Alpínid dynasty of the Scottish Kingdom of Alba. Dyfnwal's father is attested in 934. Although Dyfnwal's father may well be identical to the Cumbrian monarch recorded to have fought at the Battle of Brunanburh in 937, the sources that note this king fail to identify him by name. Dyfnwal's own reign, therefore, may have stretched from about the 930s to the 970s.

Question: Verify the following claims with "True" or "False": What is the name of Seisyll ap Dyfnwal's spouse?
Answer: False