The names of rulers in present-day Wales found in the Matter of Britain are primarily derived from Geoffrey of Monmouth's . Written about 1136, this is a pseudohistorical account of British history, drawn largely from Geoffrey's vivid imagination, though also including some elements which were taken from older sources, such as the . It includes the names of many rulers, some of whom are based on real people, though the stories that Geoffrey told about them are wildly inaccurate. Geoffrey's fictions were accepted as historical truth, and became the centrepiece of the Matter of Britain, a cycle of frequently reworked medieval tales.
In the , Geoffrey initially defines Wales as one kingdom, Cambria, which he claims to be named after its first king, Brutus of Troy's son Camber. Only one more king of Cambria is named in the : Rudaucus, several generations later. Though the term Cambria, referring to the entirety of Wales, is occasionally used later in the book, it is divided into two kingdoms: Venedotia, defined by Geoffrey as North Wales, and Demetia, defined as South Wales. These are the historical Latin names of the kingdoms of Gwynedd and Dyfed respectively, though in reality they were only two of several Welsh kingdoms.
Variations of Geoffrey's were used to dignify the genealogies of many Welsh princes, nobles, and gentry. Known examples include Gruffudd ap Cynan. In the early 15th century, Owain Glyndŵr claimed the title Prince of Wales as a direct descendant and heir of King Camber, and also of the real medieval king Cadwaladr. In 1607, the Welsh genealogist John Williams recorded the claimed genealogies of some Welsh gentry families in his Book of Baglan. The more distant "ancestors" in these lineages vary between families, but they depend heavily on Geoffrey's fictions.
In his Welsh Classical Dictionary of 1993, Peter Bartrum collates names of these legendary (and real) rulers. He supplies dates for them, appropriate for their fictitious existence. These legendary dates are of no independent historical significance.Peter Bartrum A WELSH CLASSICAL DICTIONARY. Introduction, https://www.library.wales/fileadmin/docs_gwefan/new_structure/discover/digital_exhibitions/printed_material/welsh_classical_dictionary/01_intro.pdf page 3.
Kings of Cambria NameNotesSourcesCamberSon of Brutus of Britain; became king of Cambria, while his brothers Locrinus and Albanactus became kings of Loegria and Alba respectively; fought alongside Locrinus against Humber the HunRudaucusKing of Cambria after the death of Porrex I; killed fighting alongside Staterius of Alba against Dunvallo Molmutius of Cornwall
Kings of Venedotia NameNotesSourcesGuerthaethKing of Venedotia under King Cassibelanus of Britain; fought against Julius Caesar's second invasion of BritainPeredurusKing of Venedotia; fought against Guennolous of Scotia, and was supported in this war by Merlin of Demetia and Rodarchus of CumbriaCadwallo LewirhKing of the Venedotians; attended the coronation of King ArthurMalgoKing of the Venedotians under King Constantine of Britain; had Saint David buried at St Davids Cathedral; became King of Britain, and annexed Ireland, Iceland, Götaland, the Orkneys, Norway, and DaciaCadwanKing of the Venedotians at the time Augustine of Canterbury arrived in Britain; became king of the Britons, and reached an agreement with Æthelfrith that the Saxons would rule only north of the Humber; father of Cadwalla and raised Edwin of Northumbria
Kings of Demetia NameNotesSourcesBritaelKing of Demetia under King Cassibelanus of Britain; fought against Julius Caesar's second invasion of BritainGloiusSon of the Emperor Claudius; possible namesake of Gloucester; became duke of Demetia after the death of ArviragusGrandfather of MerlinKing of Demetia; his daughter was the mother of Merlin; unnamed in the , but later sources call him Conaan, Melias, or Merlin; Brut Chronicle; ; Prose MerlinMerlinBecame king and prophet of Demetia; gave laws to Demetia; fought alongside Peredurus of Venedotia and Rodarchus of Cumbria against Guennolous of ScotiaSaterKing of the Demetians; attended the coronation of King ArthurMargaducKing of the Demetians at the time Augustine of Canterbury arrived in Britain; agreed to make King Cadwan of Venedotia king of the BritonsMargadudKing of the Demetians; close friend and advisor of King Cadwalla of Britain
See also List of legendary kings of Britain List of legendary rulers of Cornwall List of High Kings of Ireland Legendary kings of Scotland
References