The tradition of the Drowned Lands has spread through Ireland, Wales, Cornwall and Brittany (which lies beyond the Otherworld). The current versions of these tales seem to revolve around a wicked city or kingdom in a low-lying area paying for their crimes by being flooded when the flood defences are damaged. These areas have been identified as these lost lands due to remains that generally pre-date the tale by several thousand years although the Cornish losses date between the sixth and the twelfth centuries.
Although the specifics of the story have seen development, this is more-or-less how the story has been since about the twelfth century when elements of the Ys story first appeared in Brittany. Modern scholars are of the opinion that the story spread through the Brythonic cultures (see Celtic Interpretations) about when the last traces of the land that eventually appropriated the Arthurian name of Lyonnesse was lost from Cornish territories. The earliest forms are observed in Welsh and appear to date from the sixth century, before the legend of Cantref Gwaelod became firmly attached to Cardigan Bay, with a city or kingdom being lost because its wells overflowed – with no comment on the citizens’ moral standing. The versions that appear in Ireland are related to lakes but otherwise mimic these early Welsh versions.
Modern interpretation is that the earliest versions of overflowing wells actually relate to the strengthening of Otherworld connections to the point where a settlement became inaccessible, at least directly, from our reality. Although individual places always match up to the same location in the Otherworld, the geography between these connected points is much different than it is in our reality, making a community without survey data or a regular programme of exploration effectively lost. The original events may have taken place somewhere between fifteen and twenty centuries ago in order to imprint on the folklore as they have.
While locating any such lost settlements with any certainty is highly unlikely due to the amount of time that has passed, this does not prevent academics suggesting possible places that “appear” quite late in the historic records but have signs of earlier development followed by an archeological blank. One of the more well-known Otherworld Drowned Land possibilities is the lost English settlement of Cratendune.