Gwlog is shown as both the father of Elisedd (c 700) and the son of Beli (c 620) which is impossible. Gwylog married Sanan, placing him nearer the 620's.
General thought is that two generations of Powys rulers has been lost, especially in light that this was a time of massive upheaval, starting at the Battle of Chester in 613 to the recovery of Powys under Elisedd in 725.
52 - EE11
Known as the Ruin of Britain, a bad son of a good king who committed murder, rape, possibly of his own daughter. A memorial inscription to him survives in the church of Castell Dwyran, possibly his ancestral home. Regarded by Monmouth as a peaceful frugal ling who defeated the Saxons.
52 - EC6