Camelot wasn't built in a day, and neither was Arthur's legend. Here are some key dates from British history and the flowering of the Matter of Britain.

63 CE: Joseph of Arimathea comes to Glastonbury on the first Christian mission to Britain, bringing with him (according to legend) the Holy Grail.

184 CE: Lucius Artorius Castus, commander of a detachment of Sarmatian conscripts stationed in Britain, leads his troops to Gaul to quell a rebellion. This is the first appearance of the name Artorius in history. Some believe that this Roman military man is the basis for the Arthurian legend.

383: Magnus Maximus (Macsen Wledig) of Spain is proclaimed Emperor in Britain by the island's Roman garrison. With an army of British volunteers, he quickly conquers Gaul, Spain and Italy.

388: Maximus occupies Rome itself. Theodosius, the eastern Emperor, defeats him in battle and beheads him in July. The net result to Britain is the loss of many valuable troops needed for the island's defense.

396: The Roman general Stilicho reorganizes British defenses decimated by Magnus Maximus. Transfer begins of military authority from Roman commanders to local British chieftains.

406: In early January, a combined barbarian force sweeps into central Gaul, severing contact between Rome and Britain. That autumn, the remaining Roman army in Britain mutinies, and the last legion withdraws from Britain the following year.

410: Britain gains "independence" from Rome, expelling weak Roman officials and fighting for themselves against barbarian incursions.

c.438: Probable birth of Ambrosius Aurelianus, scion of the leading Romano-British family on the island.

c.445 Vortigern comes to power in Britain.

c.446: Vortigern authorizes the use of Saxon mercenaries to defend the north against barbarian attack.

c.457: Death of Vortigern.

c.458‑60: Full-scale migration of British aristocrats and city-dwellers across the English Channel to Brittany, led by Riothamus (perhaps a title rather than a name), another candidtate for the original figure behind the legends of Arthur.

c. 469: Roman emperor Anthemius appeals to the Britons for military help against the Visigoths. Reliable accounts name Riothamus as the leader of the British force. The bulk of the British force, including Riothamus, are wiped out in battle against Euric near Avallon in Gaul.

c. 470: Ambrosius assumes High-kingship of Britain.

c. 496: Britons, under overall command of Ambrosius and possibly the battlefield command of the "war leader" Arthur, defeat Saxons at the Siege of Mount Badon.

c. 496‑550: Following the victory at Mt. Badon, the Saxon advance is halted with the invaders returning to their own enclaves.

c. 501: The Battle of Llongborth. Arthur is mentioned in a Welsh poem commemorating the battle.

c. 540: Probable writing of Gildas' De Excidio Britanniae.

c. 570: Probable death of Gildas.

c. 600: Aneirin, a Welsh bard, writes Y Gododdin, alluding to Arthur's prowess as a warrior.

c. 830: Nennius compiles Historia Brittonum.

c. 970: Annales Cambriae compiled. It dates the Battle of Camlann to 542. Geoffrey of Monmouth follows this dating when writing in 1136, and adds the death (or unspecified other disappearance) of Arthur to the end of the battle.

c. 1019: Earliest possible date of composition for The Legend of St. Goeznovius, a Breton legend which mentions Arthur and calls him the King of the Britons.

c. 1090: Professional hagiographers write various saints' lives, some of which include mentions of Arthur and his exploits.

1125: William of Malmesbury completes Gesta Regum Anglorum which states:

"This is that Arthur of whom the trifling of the Britons talks such nonsense, even today; a man clearly worthy not to be dreamed of in fallacious fables, but to be proclaimed in veracious histories as one who long sustained his tottering country and gave the shattered minds of his fellow citizens an edge for war."

1129: Henry of Huntingdon writes Historia Anglorum. Ten years later, in a letter to Warinus, Henry describes Arthur's last battle and mentions that the Bretons say that he didn't die and are still waiting for his return.

1136: Geoffrey of Monmouth publishes Historia Regum Britanniae.

1155: Master (Robert) Wace completes Roman de Brut, a version of Geoffrey's "History" in French. He is the first writer to introduce the concept of the "Round Table" to the Arthurian cycle. Of Arthur, Wace says,

"I know not if you have heard tell the marvellous gestes and errant deeds related so often of King Arthur. They have been noised about this mighty realm for so great a space that the truth has turned to fable and an idle song. Such rhymes are neither sheer bare lies, nor gospel truths. They should not be considered either an idiot's tale, or given by inspiration. The minstrel has sung his ballad, the storyteller told over his tale so frequently, little by little he has decked and painted, till by reason of his embellishment the truth stands hid in the trappings of a tale. Thus to make a delectable tune to your ear, history goes masking as fable."

c.1160‑90: During this period, Chretien de Troyes makes his contributions to the Arthurian cycle, including Lancelot, Camelot, and the Holy Grail for the first time.

1184: Great fire ravages Glastonbury Abbey, destroying Old Church. "Arthur's Grave" is discovered at the Abbey six years later.

c.1190: Layamon publishes Brut, an English translation of Wace into alliterative verse. His work marks the first appearance of the Arthurian story in English.

And so on, to the present day....