In transformers cybertron series, where did the decepticons go to when they opened the red space bridge? it looked like hell or inside a volcano or something.
When Unicron was defeated in the end of Energon, they got sucked into that dimension. They just figured out how to move back and forth through it in Cybertron. It wasn't fleshed out very well, but that was my guess.
In Galaxy Force, it's named "Fire Space" and there's no explanation given for it. It just exists. Because the Japanese have more imagination than Western people who need an explanation for everything.