The Green (2009)

From the back of the book:

The Green..
Some say it began as a garden planted by the old gods themselves when the worls was young, so they could shade themselves from the fiery sun and take rest from their divine pursuits. Others maintain that a strong, healthy magicinfuses the mountain waters that feed it, giving it's flore and fauna their prodigious health and size. Still others have called it a verdant hell where the spirits of the prideful ans cursed are damned to spend eternity among the incects, hounded by venomous predators. perhaps there is a truth to each..

Detailing a massive rain-forest basin, it's inhabitants, cultures and secrets. Suitable for play by itself, or added to an existing fantasy-world. Or perhaps as a fantastic lost world for modern adventurers..