It is often associated with the Vikings and the Viking Age. The term is used in Welsh texts to describe the lands and peoples of these northern regions, and it is sometimes used interchangeably with the term “Loegria,” which refers to England.
In Welsh literature and history, “Llychlyn” is often depicted as a distant and mysterious land inhabited by formidable seafaring warriors (the Vikings) who occasionally interacted with the people of Wales and other parts of the British Isles through trade, raids, and conflicts.
In Culhwch and Olwen, Glewlwyd, Arthur’s gatekeeper, says that
in the contest between the two Ynyrs - twelve hostages were brought from Llynchlyn.
A Welsh Triad names the earl of Llychlyn as the father of Arthur’s warrior Blaes.
Culhwch and Olwen | Late 11th century
Triads of the Island of Britain (Welsh ”Triads”) | 11th century to 14th century