The "Impact Zone" is the location where a meteor impacted the continent. The force of the impact created a massive earthquake which divided the continent into 4 masses, turning the water radioactive, and cutting off the inhabitants from each other. Cut off from each other each group were free to evolve into their own unique civilization.  Centuries after the impact the "Impact Zone" had cooled enough for expeditions to begin. Explorers returned with tails of Danger but also of news of Great wealth for those brave enough to adventure into the zone. With needed resources running low it was time for the 4 great civilizations to meet each other face to face on the battle field.