I’m probably wrong, but my first thought was:
North, South, West, and East from one version of Oz
North, South, West, and East from another version of Oz.
In the books, Oz originally had four wicked witches. Then the GWN and Glinda conquered Mombi and the WWS, respectively (Mombi is known to have lived).
On OUaT, we see a GWE, and Dorothy was given a seat on the Witches’ council (West), so that’s something to consider. Mombi was mentioned (by title, not by name) in “Where Bluebirds Fly,” taking the narrative place of the WWE in the Tin Man’s origin story (and the Tin Man’s name was changed from Nick Chopper to Stanum).