The Magic of Oz by L. Frank Baum

In the central western part of the Gillikin Country is a great tangle of trees called Gugu Forest. It is the biggest forest in all Oz and stretches miles and miles in every direction -- north, south, east and west. Adjoining it on the east side is a range of rugged mountains covered with underbrush and small twisted trees. You can find this place by looking at the Map of the Land of Oz.

Gugu Forest is the home of most of the wild beasts that inhabit Oz. These are seldom disturbed in their leafy haunts because there is no reason why Oz people should go there, except on rare occasions, and most parts of the forest have never been seen by any eyes but the eyes of the beasts who make their home there. The biggest beasts inhabit the great forest, while the smaller ones live mostly in the mountain underbrush at the east.