Well, he's definitely aware of the existence of Dragons. There were two (a gold and a silver) who served Oberon, and Andere (his wife) in what is now Caer Albion for a long time. Uther (gold) and Aureliana (silver).
But your character would have known of them as well.
Aureliana is believed to have died in the Freedom War in a battle against Mordred's forces, Uther is believed to have died while serving the Bluestar in the War of the Damned. At the very least, neither have been seen for approx. 900 years.