>>46282601Judging by the ancient-looking monoliths scattered around that region of the map, I’m guessing the ancient galarians who settled there witnessed a gigantic G-Max Toxtricity during the Darkest Days, perhaps the very first recorded instance of a G-Max transformation.
They made that mural, and scattered those monoliths around for... reasons, I don’t know, Game Freak prefers aesthetics over lore, so they rarely address these things indirectly. There must always be a character who explains boring things, like that fake wall drawing that Bede broke to reveal a hidden statue, but never the interesting stuff.