In the medieval Welsh romance Culhwch and Olwen, Din Tywi is mentioned as one of the locations associated with the story’s protagonist, Culhwch. The tale is part of the collection known as the Mabinogion, a compilation of Welsh prose tales that include mythology, legend, and folklore. Culwhch and his companions hunted a piglet known as Grugyn Silver Bristle in this area.
Din Tywi refers to the Kingdom of Dyfed, which is located in the southwestern part of Wales. It was one of the significant Welsh kingdoms during the early medieval period. Dyfed is situated in the present-day counties of Pembrokeshire, Carmarthenshire, and Ceredigion.
Notes
Din is an ancient Welsh word for a fortified hill, a camp – hence we have our dinas, a fortified town or city. The English denizen probably derives from this word. Professor Rhys groups the Irish word dun, the Anglo-Saxon tun, and the English town, with the Welsh din. The Romans’ words dunum, dinum, and dinium are probably allied with it as well.
Source
Culhwch and Olwen | Late 11th century