One of a maps first set of purposes was to show troop movement and or territorial boundaries during ancient times. The would show the land owned by a King or nobleman and sometimes those very same maps would cause a dispute which resulted in war. Check out this article on how Google Maps and other map applications change the boundaries based upon a person IP address or geographical location. Talk about political correctness.
Here is a portion of the article:
At the other extreme, some territorial disputes involve land that would seem entirely worthless. The U.K., Iceland, and Denmark all assert ownership of Rockall Island, an 8,000 square foot rock in the middle of the North Atlantic, hundreds of miles from the nearest inhabited location.