(Sheds some light on Arthur the Warrior King who fought the Saxons).
There is only one contemporary Arthurian source that can be examined today. "Concerning the Ruin of Britain", or "De Excidio British History Clube" was written by the Northern British monk, St. Gildas, in the mid-6th century. Unfortunately, Gildas was not a historian. He was only interested in lamenting the loss of the Roman way of life and reproaching the British leaders (Constantine, Aurelius Caninus, Vortepor, Cuneglasus & Maglocunus) who had usurped Imperial power and degraded Christian values. There is no reference to Arthur, but Gildas does make reference to a character called "The Bear", the meaning of the Celtic word, Art-. He praises Ambrosius Aurelianus and also mentions the Siege of Mount Badon, though not the name of the victor. Gildas' writings are dated immediately prior to 549 (the death of Maglocunus, one of his usurpers). The passage telling of Badon places the siege forty-four years before this. This places Arthur firmly around the turn of the 6th century. (See Alcock 1971).
The Welsh Easter Annals or Annales Cambriae, supposedly written over the years that they cover, AD 447 to 957 (though very early entries were probably written some time after the events), are amongst the earliest sources to mention Arthur. Used to calculate Easter dates, this document also records historical events alongside many of its yearly entries. Two of these tell of Arthur. AD 516 refers to "The Battle of Badon, in which Arthur carried the Cross of Our Lord Jesus Christ for three days and three nights on his shoulders and the Britons were the victors". The entry for AD 537 records "The Strife of Camlann in which Arthur and Medraut perished". All characters included elsewhere in these, otherwise reliable, annals appear to have been real historical people. There is no reason to suppose, therefore, that Arthur and Mordred were not likewise. It has been suggested that stylistically speaking, Arthur's appearance in the Badon entry may have been an interpolation. Criticisms of the length of the battle are unfounded though, for Gildas (see above), more correctly, calls the battle a siege. The statement that Arthur carried "the cross of Our Lord on his shoulders" may refer to an amulet containing a chip of the true cross. Or more likely it is a transcriptual error of Welsh "shoulder" for "shield", indicating the cross was merely an armorial bearing. (See Alcock 1971).
Arthur does warrant a passing comment in the early 7th century poem Y Gododdin by Aneirin, the famous bard from the Royal House of the North Pennines. This work praises the efforts of the Northern British armies, headed by those of Din-Eityn and Gododdin, at the battle of Catraeth around AD 600 and one warrior is described as having "glutted black ravens on the ramparts of the fort, although he was no Arthur". It has been argued that this shows the early spread of Arthur's fame. Unfortunately, considering the northern overtones, this may refer to the Arthur's Northern contemporary, King Arthwys of the Pennines.
The last major Arthurian reference occurs in the 8th century "Historia Brittonum" or "History of the Britons", apparently written by a Welsh historian called Nennius, possibly a monk from Bangor Fawr (Gwynedd). Nennius used numerous chronicles to put together this compilation history of the British peoples, followed by genealogies and a list of the 28 Towns of Britain. The work is particularly noted for its chapter concerning the Campaigns of Arthur, telling of his twelve battles. These latter may be a Latin summary of an ancient Welsh battle list, possibly pre-dating the unmentioned Battle of Camlann. Was this sung at Arthur's Court? Each battle is named in turn, but the enemy is not specific and the places are difficult to identify. Nennius states that at all the battles, Arthur fought them, implying the previously mentioned Kentish Saxons, though this seems unlikely. (See Alcock 1971)