Some ten million years after the 21st century, Sol went supernova. This deprived humanity of their common cultural reference point. Thus since they were post-Earth, they were posthuman, forming what became known as the posthuman hegemony.
The second and larger group felt the reverse, no longer bound to their ancestral home's traditions. They operated on whim and decadence, the most prominent display of which was Siloportem. (PROSE: The Book of the War)