Board Thread:Spoilers!/@comment-6175354-20140212194028/@comment-32390199-20140318223818

No Dorothy didn't create Oz. There is a whole complicated thing behind Oz that had to be explained in multiple books. I don't think they can pass it off as another dreamrealm like Neverland.

And I think that Cora and Leopold wanted to forget their relationship/affaire together so they send Zelena to Oz. I don't know how much time passed between Cora marrying Prince Henry and Regina's birth.