Not actually a zone, but rather the lack of one. It's a former void of nothingness where the first thing began existing, The Birthday Cake. For a while the cake was the only existing thing and it enjoyed being that way. It all changed when the cake began to feel unwell. Mold has started to decompose it and other things kept flagrantly existing. These were simple beings and later more complex ones came to be. The zones were also formed from this starting point. The cake was revolted by the existence of other things, especially for not being cake. After its decomposition only The Crumbs remained. The crumbs remember the cake and formed the Parliament in their mission to put an end to existence, returning to the oneness of the cake.
The story of the cake and the beginning of existence can be read in this book.