The Sage World Earth of millennia ago wasn't known to be a unified world.
Each Noble House serves as an overlord of their own region, dominating the denizens in their jurisdiction while competing with the other three prominent regions.
They're like the superpower countries of our modern world.
Genbu of the North.
Seiryuu of the East.
Byakko of the West.
Suzaku of the South.
Kouryuu, as a fallen Noble House, whose region bordered all four of them failed to withstand the pressure, resulting in their recovery to never come into fruition.
Perhaps if not for Huang and the other Sage Ranks their fallen Noble House managed to produce, the Central Region – which was the current Earth – would also be divided by the four regions.
In any case, thanks to me, all of those four regions were severed from the Sage World and left to rot in the wide Chaotic Space.