Wild Heart Isle was one of the few islands with a very low human or demon population. There would be some teleportation arrays set up for use as well as connection bridges but outside of that, they were left alone.
Unlike in the lower world, aether beasts achieve a level of intelligence to band together and unify against the other races. Unlike other cultivators, aether beasts did not need techniques, or other normal activities humans, demons, and aether children needed to advance.
They just needed the life and death struggle to advance. While some beasts could learn techniques, they usually only needed to rely on their instincts and strength. All of the Sky Realm that held true so it was not unusual to have tier 8 or 9 Sky Realm aether beasts in large numbers.
Thus, several isles have been claimed by them and refused all attempts to invade them.
