Region in Ferania. The magical forest of the Green Gnomes and other Lilliputian creatures. The place of many legends. Even the travel diaries refer to the tiny, underground gnome city (the Reverse City) which could be only accessed by taking in the special potion that shrinks you down in size.
Very few, (according to some Trunket testimonies), have had a chance to visit it and return, because not many knew about the potion for de-shrinking you back in size. Leaving all the poor journeymen to remain in the tiny city, perhaps forever. And maybe some of them had made that choice on purpose.