Eudaf Hen - The Dream of Macsen Wledig

Although the Mabinogion tale Breudwyt Macsen Wledic (The Dream of Macsen Wledig) is written in later manuscripts than Geoffrey's version, the two accounts are so different that scholars agree the Dream cannot be based purely on Geoffrey's version. The Dream's account also seems to accord better with details in the Triads, so it perhaps reflects an earlier tradition.

Macsen Wledig, the Emperor of Rome, dreams one night of a lovely maiden in a wonderful, far-off land. Awakening, he sends his men all over the earth in search of her. With much difficulty they find the maiden in a rich castle in Wales, Segontium (Caernarfon), and lead the Emperor to her. Everything he finds is exactly as in his dream, including the presence of her young, gwyddbwyll-playing brothers Cynan (Conan Meriadoc) and Gadeon, as well as her father, king Eudaf Hen, son of Caradawc (Caradog ap Bran). The maiden, whose name is Helen or Elen Llwyddawc, accepts and loves him. Because Elen is found a virgin, Macsen gives her father sovereignty over the island of Britain and orders three castles built for his bride. In Macsen's absence, a new emperor seizes power and warns him not to return. With the help of men from Britain led by Cynan and Gadeon, Macsen marches across Gaul and Italy and recaptures Rome. In gratitude to his British allies, Macsen rewards them with a portion of Gaul that becomes known as Brittany.