The setting of CoC is a single massive Caldera that rivals that of Earths largest. Flowing from the wall of one side of the Caldera is a single massive waterfall that supplies the area with most of its fresh water. Forming a large river system from its base, it feeds into a giant lake at the caldera's center. Surrounding this lake are a number of small villages and a number of thick forests. The land of the caldera is imperceptibly slanted down from the lake, turning the area beyond it into increasingly marshy swampland.
Within its massive depression is a wide range of peoples that would normally get on with their daily lives. Two large city states are located along the caldera walls nearly opposite one another. Engaging in almost constant war across countless ages, they are not only long standing enemies but they embroil all the land between them in their conflict. From the wide swaths of farmland that supply food to either city to the traders that move up and down the river with goods, there is not one soul that has been untouched by war.