I'm just guessing -- but I've been reading about compass points, direction and maps on wikipedia -- and here's my theory why North is at the top of the map, and not south... it's not really arbitrary -- China invented the compass (not exactly, but they're the ones that figured out there are magnetic poles, and they did rely on it for navigation for over 1000 years, before the europeans figured it out in the 1300's, and made a trusty tool called a compass, used for navigation. (The chinese magnetized a pin with silk, placed the pin in a straw, dropped the straw in a bowl of water, and watched which way the straw pointed, they knew it could point only north or south). Here's the theory: people that lived in the southern hemisphere didn't get lost as much, because predictable wind patterns and clear skies aided navigation. If they looked up, they knew where they were. In the northern hemisphere it was often cloudy, and they didn't have predictible monsoons to help their navigation, so they needed tools: a compass and a map. Since they were in the northern hemisphere, the compass points north, and hence it is placed at the top of the map.

1) "A reversed map, also known as an Upside-Down map or South-Up map, is a world map that generally shows Australia and New Zealand at the top of the map instead of the bottom. Indonesia is placed in the center while Europe and the Americas are placed to the sides, although there are reversed maps centered on the Prime Meridian. They are used as tools for teaching critical thinking. The position of North at the top of maps is somewhat arbitrary; indeed there are many maps with non-standard orientation, such as Medieval maps, polar maps, and Dymaxion maps. The convention that North is at the top (and East at the right) on most modern maps was established by the astronomer Ptolemy and was widely adopted by other cartographers." "The famous photo of Earth from Apollo 17 (Blue Marble) originally had the south pole at the top, as in this view, with the island of Madagascar visible just left of center, and the continent of Africa at its right. However, the image was turned upside-down to fit the traditional view." Source and further information: http://en.wikipedia.org/wiki/Reversed_map 2) "The convention came a few centuries ago when Northern hemisphere, European navigators started using the North star and the magnetic compass. Before that, the top of the map was to the East which is where the word orientation comes from." "Arabia (Ancient): They put south at the top. This is because when you wake up and face the sun, south is on the right. Because of positive associations with the right as opposed to left, they put that on top. Yemen is so named because it is on the "yamin" right of Arabia. And of course, with the sea to the south of them there was nothing "on top" of the country, so they prefered it that way. Europeans learnt mapmaking from the Arabians and flipped the map to make themselves on top." "Arctic/Antarctic: A natural map of the poles has either south or north at the top and at the bottom - indeed, in all directions. Unusually, the opposite compass direction will be located in the centre." "Australia: Maps are pacific centred." "Biblical Times: There is evidence from the Torah that east was at the top of maps." "Medieval Europe: Jerusalem was on top because that was the Holy Land. This meant that east was more or less at the top." Source and further information: http://flourish.org/upsidedownmap/ (With some other examples)