The distinction between great and small worlds does not lie in their size, but in the presence of Chaos; small worlds are not entwined with Chaos.
The Three Thousand Great Worlds appear like inverted discs, with a ring of rolling Chaos at their edges. The great worlds constantly collide with Chaos, giving rise to new mountains and territories.
But this process is exceedingly slow, and the fragile parts may be eroded by Chaos, with mountains and rivers becoming part of it.
Divine beasts not only help suppress the Chaos in great worlds but can also cleave through it to form new mountains and rivers. This is why worlds treasure divine beasts so dearly.
Compared to the Sealed Emperor Great World and the Mystery Huang World, the two oldest worlds, other great worlds are much more fragile and in greater need of the suppression by divine beasts.
