In his work "On the Ruin and Conquest of Britain" written , Gildas makes an allegorical condemnation of five British kings by likening them to the beasts of the Book of Revelation 13:2--the lion, leopard, bear, and dragon, with the dragon supreme among them. He says that Maelgwn is the "dragon of the island", and goes on with a litany of moral accusations, in the process describing him almost as a regional high king over the other kings (the power-giving dragon of the Apocalypse). The Isle of Anglesey was the base of power of the kings of Gwynedd, so describing Maelgwn as the "dragon of the island" is appropriate.