yeah even in pathfinder its a little different. drow are elves that went underground during earthfall while the good elves went back to their planet (yes, elves are aliens). the drow went insane because rovagug, the eater of worlds, is imprisoned in the core of golarion and has a greater influence the deeper down you go. earthfall itself was a bunch of asteroids being flung at the planet by tentacle space fish, the asteroids themselves physically killed a couple of gods

fun fact, golarion means god cage in some random language