I don't know if this is how the game is or if a map is missing, I have forest, forest 2 and dungeons. I've completed forest 2 (Orc Village) 100% but I thought I saw a message about a new area.
The 'new area' message is coded into everything once you finish and doesn't actually check if there is another area to unlock... I should probably change that... I'm hoping to add a 3rd exploration zone in this next update, but I'm not sure if I'll have time. It's at the bottom of the list.