I've been trying to catch all the Tapu's, but I can't seem to find the Ruins of Abundance at all. I know it's in the Haina desert, but I keep getting all mixed up in there and end up back at the beginning. I did however find the man in the desert who said he had amnesia, but he did remember one Pokémon (which was Lunatone), and if he saw it he might remember more. I'm not sure if that's connected to the Ruins at all, but anything helps I guess.