From PathfinderWiki

The evergrowth is a verdant swampland filled with a huge variety of plants not found anywhere else in Katapesh, a natural wonder and a naturalist's dream.

Evergrowth is covered in a canopy of verdant green growth shot through with beams of sunlight. It teems with life, and is filled with a wide variety of insects, reptiles, birds, and small mammals. Unfortunately, this abundance has led to fierce creatures that prey on this life, like gnolls and the only kobolds in all of Katapesh, making the evergrowth their home. Despite these dangers, there are no end to the people willing to venture into the swamp to find rare herbs and plants.1