Arthuret is the Latinised form of the Welsh word Arfderydd.
This is the schene of a battle, about the year AD 575, in which Rhydderch Hael defeated Gwenddolau. Merlin is said to have taken part in the battle, traditions vary as to the side he was on, and supposedly went insane because of a vision he saw in the sky there.
Despite the name, it is unrelated to Arthur.
Welsh | The Legend of King Arthur