User blog comment:Xhatefate/DxD Updates~/@comment-16281343-20150801105410/@comment-16281343-20150809134402

A dimension that a particular group of magicians live in located in the Dimensional Gap. Thus, Wizards of Oz.

inb4, are they related/based on/taken inspiration from the "Wizard of Oz".

It most definitely is. One of the artificial independent avatar-type SG they created was named "Cowardly Leo".