The Great Rift is a wall of mountains which was form due to Durza's attack which caused the tectonic plates to rise. This landmass is located in the middle of the First, Second and Third seas. It is also the main reason why the Arcane Government cannot fully access the Third Sea, which only has two access points, from the far north and the far south. Both which are not close enough to a large AG facility that could supply reinforcements or communicate quickly.