Stone carvings and tablets depicting the battles, but then again, they also claim to be magic. That instead of cards, the monsters were locked away in stone, to be summoned by the priests of the pharaoh.

I think it's nonsense, of course, but if nothing else, the game was inspired by these stories and depictions. Some cards even have ancient script on them that needs deciphered first to be used effectively. All for show, I'm sure. [He's still nnnnnot touching the fact that he could read ancient Egyptian script on Ra's card without needing the computers to fully translate it. That doesn't bother him at all.]