Denmark
Danemarce, Danemarche, Danmark, Denmarch, Denmarke
During the Arthurian period, Denmark was populated by collections of Scandinavian clans. The united country of Denmark (Dane-marche, "borderland of the Danes") did not exist until the ninth century. No such history prevents the "kingdom of Denmark" from appearing in the Arthurian legends, however.
According to Geoffrey of Monmouth, Arthur conquered Denmark and gave it to Aschil, one of his noblemen, whom supported him in his last battle. In Wace, Aschil is the ruler of Denmark already, but subjugates himself to Arthur’s rule in order to avoid a hopeless war. Geoffrey Gaimar (a twelfth-century Welsh writer) has Arthur conquer Denmark by killing King Gunter, whose brother, Odulf, subsequently claimed the throne. Another Arthurian tale features a king of Denmark named Tryffin.
Welsh legend also makes Arthur ruler of Denmark, naming Yder as one of his Danish warriors. The Didot-Perceval names its king as Guillac, who assists Arthur in the Roman War. In the Vulgate Merlin, on the other hand, Denmark is ruled by the Saxon kings Aminaduc, Rions (Ryons), and Bramangue, who are defeated by Arthur.
In the Post-Vulgate Merlin continuation and in Malory, an unnamed King of Denmark (who is the brother of the King of Ireland) invades Britain with four other rulers, and is killed at the battle of the Humber. In the Welsh Triads, the King of Denmark is the father of Arthur’s warrior Nasiens. In Claris et Laris it was ruled by Heldins, then by Tallas who besieges King Urien but is defeated by Arthur’s knights and succeeded by Laris. A Queen of Denmark, who hates the Round Table, is the ruler of the Castle of Maidens in the Livre d’Artus, the romance also mentions a Saxon named Aminaduc as king of Denmark. Morte Arthure says Mordred made the Danes his allies. Durmart calls the king Jozefant.
Various references are made to this country's rulers in Arthurian tales. It is not possible to say who was actually in power in Denmark in the Arthurian period: the first definitely historical king of all Denmark was Gorm the Old who commenced his reign about the year AD 900. Danish traditional lists go much further back, claiming there were various smaller kingdoms in Denmark before unification under Gorm, notably that of Lethra which had a list of kings going back to Skioldr, son of Odin.
In Anderson's 'Royal Genealogies', kings of Denmark in the traditionally Arthurian period were Harald IV (AD 481-527) and also Eschyllus (AD 527-543).Five Kings | The Legend of King Arthur
Godfrey | The Legend of King Arthur