Cyngen married St. Tudlwystl, a daughter of Brychan ap Gwyngwen ap Tewdr (often confused with King Brychan Brycheiniog) and they were parents of a large family: Brochfael Ysgithrog, Cadell, Ieuaf, Maig Myngfras, Mawn and Sanan.
[1] The nickname under which Cygen is remembered is rather ironic considering that he may have appeared in Gildas the Wise's De Excidio Britanniae (of which he was a contemporary) as "Aurelius Caninus" (i.e.: the Dog).
He would then be the second of the five kings castigated by Gildas, who accused him of fostering civil war in Britain.
On the other hand, Cygen is also remembered for his rich patronage of many saints and his donations to the church, placing him in a similar position to his contemporary, King Maelgwn of Gwynedd.
It is not known when Cyngen died, but what is probably his tombstone used as a barrier at Tywyn was discovered in 1761, and he may have been buried with Saint Cadfan.