You're an Orrean native that went to university out of region due to the largess of your grandfather. Grandpa had made his money on mining, but in his old age he'd become a bit of a laughing stock, claiming that Orre's pokemon were still there. But they'd gone underground after the area was devastated by a cataclysm in ancient days.
He'd tell tales about having encountered pokemon in different caverns and caves, places where light was provided by massive Sunstones or heated by Fire Stone...