The canon for that well-known fanfic, The Shining Company.
The National Library of Wales have digitised their original copy of the Book of Aneirin which holds the original story of the Gododdin*. This copy is still 6-700 years newer than the battle, and the presentation - all those twirly reds and greens - perhaps suggests that this is already part of the story that Wales tells about itself.
My Welsh is sadly not good enough to read it, but I'm interested that I can manage to pick out words and names here and there...
*had to look up how many 'd's in Gododdin, but I'm not sure why I did this given that on page 1 of this manuscript it's clearly spelt gododin, and on the 19th century flyleaf it says Gododyn and spelling is such a creative pursuit in the middle ages. :-D
My Welsh is sadly not good enough to read it, but I'm interested that I can manage to pick out words and names here and there...
*had to look up how many 'd's in Gododdin, but I'm not sure why I did this given that on page 1 of this manuscript it's clearly spelt gododin, and on the 19th century flyleaf it says Gododyn and spelling is such a creative pursuit in the middle ages. :-D