Sexes, Xerxes
The King of Iturea or Idumea who was subservient to the Roman Procurator Lucius.
Serses was called upon to join Lucius in the war against Arthur. He led a force of soldiers at the battle of Soissons.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century