Quite a few books, legends, poems and stories abound about Merlin and the Arthurian legends. Not all of them from the British Isles. “Orlando Furioso” is pretty good, Merlin, Mordred and Morgan Le Fey all show up several times in it, as well as mention of Arthur and various knights. It tells a set of stories about the period of Charlemagne and the driving of the Muslims from France and Europe.
I was amazed that the scope of the tales take in everything from Arthus’s Court to the Emperor of Cathay.
My kind of bedtime stories... ;^)