Boards matching the Nine Men's Morris grid are scratched into stone across Africa, Asia and Europe, some far older than the game's own securely dated literary record, but a carved grid alone does not prove play took place at that site or identify which culture first originated the game.
What would resolve this A securely dated depiction or written description of actual play, earlier than every rival claim, which has not been identified.
OpenArchaeologyThe Oxford History of Board Games