Zaxborg is a Meta-Celestialsapien, a Celestialsapien without a pocket universe and the personalities. He is the ruler of Dimension M, a dimension almost isolated except from Earth, where he made a secret portal millions of years ago.
Zaxborg was an incomplete Celestialsapien upon his birth at the Forge. So the Celestialsapien king banished him and brought him to Earth. There he cloned himself into thousands, and formed a secret clan called the "Celestial Clan". With many humans living on earth Zaxborg decided to create Dimension M to maintain their secrecy. He built a portal to the dimension and made a land there.
Millions of years later humans discovered the portal, still active. They entered the dimension. Zaxborg decided to let them in.