The Isolated Dimension is a Reality contained by the Metareality-Web. It has a repulsive barrier around it so strong it that all Metareality-Links that were once connecting it to other realities were immediately destroyed and the space inbetween was pushed out leaving Nothing all around the universe making it impossible to enter without teleportation.
Even then the chaotic nature of the reality itself makes living in there, impossible. as such The Isolated Dimension is a desolate reality with no civilizations, or even stable particles for that matter.