The sea level was low enough around 1600 AD to make the claims of Sir John Wynne of Gwydir feasible.
[2] Legends developed about it suggesting that it was the palace of Prince Helig ap Glanawg (also spelled Glannog) who lived in the 6th century, and whose sons established a number of churches in the area.
He owned a large area of land between the Great Orme's Head near Llandudno and the Menai Strait off the north coast of Gwynedd.
[citation needed] Llys Helig is mentioned in a number of old documents, some of which were published after expeditions to find the Palace.
[citation needed] Rachel Bromwich discusses what she refers to as the folk-tale of Cantre'r Gwaelod, another alleged sunken kingdom but in Cardiganshire.