I'm writing this right off the top of my head right now. The region was once, many many years ago, invaded and laid claim to by ancestors of Kalosians, (the warring type they are) and a group of soldiers made their way up a mountain near the center of the island. Finding it home to an Altaria and it's children, but also an abundance of raw material, they fought the Altaria for it, killing it. Xerneas of Kalos, horrified by this event, gives one of the Swablu children the power to defend the region. Encasing it in scales tougher than the primitive spears the soldiers of Kalos wield, and giving it the power to breathe fire to scare off all who wish to exploit the land, Swablu was transformed into a dual Fire/Dragon type. The Kalosians fled with their tails between their legs, and there was peace on the island for a very long time. Until it was rediscovered by Hoenn researchers. Swablu, seeing this research ship approaching, is reminded of the Kalosian warships and whips up a storm to steer them off course. This failing, it goes in personally and destroys the boat, leading to our Hero washing up on the island's beach.