"Then the king came with his wizards to seek the stronghold, and encompassed many countries and many provinces, and did not find it, and at last they came to the country called Gwynedd; and when he was exploring in the mountains of Eryri, that is, in English, Snowdon, he at length reached a place in one of the mountains that was suitable for building a stronghold. So his wizards said to him 'Make a stronghold in this place, for it will be for ever safest against the barbarian peoples.'"
Nennius, Historia Brittonum
The figure of Ambrosius Aurelianus who, in Gildas, rallies the beleaguered British against the Saxon invaders so foolishly invited there by Vortigern, is, in Nennius, a latter rival of Vortigern, who, awed by the prophecies of the young Emrys (Ambrosius), gives him the fortress of Dinas Emrys and lordship over western Britain.
Geoffrey of Monmouth later identifies Emrys with a character of his own: the magician Merlin. Ambrosius now is Aurelius Ambrosius, a brother of Uther Pendragon, who defeats both Vortigern and Hengest. He is buried at Stonehendge, which Merlin magically transports from Ireland.
