King Arthur or Anabaptists, What's Easier to Prove for 6th Century?

This link suggests that proving King Arthur is if not yet totally done, at least vaguely possible:

Exciting New Evidence Proves King Arthur Is A True Story After All
By Meagan Nantwich, Dec 5, 2018
http://www.noteabley.com/culture/king-arthur-evidence-tb/

It's far less easy to show up anything beyond obvious misunderstandings and names with no documents prior to Reformation in order to substantiate some kind of Anabaptist Christianity on the lines of Baptists or Mennonites, even roughly, for that time.

I said "beyond obvious misunderstandings" - since you obviously can misunderstand Culdees as sth different than basically Catholic monks (no more or not much more different from Catholics than Russian Orthodox are) and you can misunderstand the canons Germanos of Constantinople gave for baptism as not just written mainly for adult baptism, but as therefore positively excluding child baptism.

And I said "beyond names with no documents prior to Reformation", as when for 8th C. I saw one fairly made up story about two "Anabaptist" or "Non-Papist" martyrs Clement of Scotland and Albert of Gaul, in Martyrs' Mirror.

King Arthur is documented prior to that./HGL