The Barian World was once part of Astral World and was created with the purpose of hosting any soul that possessed the power of Chaos. The world was originally small, but later expanded due to all the souls that were caught in the middle of Nasch's ancient battle against Vector.
The Barian World is a world made of various powerful energies resembling the Astral World, but with a darker color scheme. Like the Earth, the Barian World experiences rainstorms on occasion. Unlike Earth, Baria Crystals occupy most of the Barian World, as do red tundras.
When Dr. Faker entered the Barian World by sacrificing two people - Kazuma Tsukumo and Byron Arclight, he was met by Vector. Vector agreed to use the powers of his world to sustain the life of Faker's son Hart Tenjo. In exchange, Faker was to destroy the Astral World. To that end, he began gathering "Numbers" to power the Sphere Field Cannon. However, he told other people he made the pact with Vector in order to conquer the world. Faker's son, Kite Tenjo, owns a robot called Orbital 7, which was fueled by Baria Crystal, a fuel from the Barian World. Although Faker did not tell Kite the whole story, he was at least aware that the Barian World existed and was related to the "Numbers" in some way.
Byron Arclight (who eventually became known as Vetrix), was rescued by a group of Barians and granted the abilities of the Barian World. His saviors requested that he collect the "Numbers" and destroy the Astral World as compensation for their help. These abilities included the power to restrain opponents with chains, and ownership of the card, "Final Prophecy", which is capable of opening the doorway to the Barian World. Vetrix said that he trusted only two things - himself and the Barian World, as they are what protected him after being betrayed by Dr. Faker.