King Arthur is first mentioned in Welsh literature, notably in the poem 'Y Gododdin' and in the 'Historia Brittonum', which attributes twelve battles to him.
Geoffrey of Monmouth publishes 'History of the Kings of Britain', which popularizes the legend of King Arthur and introduces many elements of the Arthurian mythos to a wider European audience.
French poet Chrétien de Troyes composes several iconic Arthurian romances, including those featuring the Knights of the Round Table and the quest for the Holy Grail.
Thomas Malory compiles and reworks the Arthurian legends into the seminal work 'Le Morte d'Arthur', which becomes the definitive English version of the stories.