The name Cynan Wledig appears in its Latin form as Aurelius Caninus in the De Excidio where it is listed as one of five tyrants alive at the time of Gildas. Their territories were as follows:
? (Aurelius Caninus),
Gildas’s list follows a geographical progression which suggests Cynan ruled over an area of South Wales. Bartrum suggests Aurelius Caninus could be identified with Cynan Garwyn of Powys. He adds that there is no consensus as to which kingdom he ruled. The king would have been of gen. 0 or 1, as were the other tyrants mentioned by Gildas, suggesting that he may have been Cynan ap Casanauth Wledig of Powys, see JC20 16b at Sanan ferch Elise.
The five rulers appear in the DEB after the Ambrosius passage. They may have inherited their kingdoms from Arthur who had succeeded Ambrosius:
brenin Emrys y bumran
King Emrys of the Five Parts
HB 42 states tells us that Vortigern gave Emrys Wledig all the kingdoms in the western part of Britain. Triad 1 tells us Arthur ruled over Gwynedd, Cornwall and Pen Rhionydd. The last name is likely to be in Rheged and, therfore, chronology suggests Aurelius Caninus is likely to have been Cynfarch Oer, the father of Urien. Koch derives Cynfarch from a name which literally means hound-stallion. So here we have another example of Gildas’s name play.
 Arch. Camb. vol. 6, 239. NLWJ vol. 18 no. 4, 412 and 414.
 Bromwich, R., 2006, 1.
 Koch, J.T., 2006, 537.