Llongborth is an ancient name for a location in Wales that is sometimes associated with modern-day Llanwit Major in the Vale of Glamorgan. However, there is some uncertainty and debate regarding the exact identification of Llongborth.
The name appears in early Welsh texts, including the Mabinogion, a collection of medieval Welsh texts. In these texts, Llongborth is often mentioned in the context of legendary stories, particularly those involving King Arthur and his knights. In some versions of the Arthurian legends, Llongborth is described as a coastal town or harbor.
The Red Book of Hergest says Gerint (Geraint, king of Devon) the hero of a battle, was killed here, but the preferred text of the Black Book of Carmarthen does not mention this. One line alludes to Arthur, though it is unclear whether it is indicating that Arthur himself was at the battle, or whether only Arthur’s men were there.
Llongborth may be identified with Langport in Somerset or Portchester on the coast of Hampshire. Portchester was the site of a battle between the Saxons and the Britons in 501, according to the Anglo-Saxon Chronicle.
See also
Girt Dog of Langport | The Legend of King Arthur
Source
Geraint filius Erbin | 10th century or 11th century
Anglo-Saxon Chronicle | 9th century