Board Thread:Lore Discussion/@comment-125.251.12.3-20141118131033/@comment-9212235-20141118204039

You pretty much have it. Anu dreams and his in is fractured into Anu and Padomay. The interplay between the two halves creates the Aurbis. A simple way to think of it is two overlapping circles. The overlapping part is where the Aurbis is.

There's also a school of thought that Oblivion is Sithis and Aetherius is Anui-El. As they are the Aurbical manifestation of Anu and Padomay.