One Ruler on Earth is a modification for Medieval II featuring a world map with 30 playable factions from the Americas to Japan. The campaign begins in late 1204, after the Fourth Crusade and just as the clans of Mongolia are being united under Genghis Khan, and ends in the 17th century. It features hundreds of new units and complete rev of the vanilla factions, as well as unique building trees and events on the campaign map.