The Global Map represents the entire world. The world is wrap around so if you go off the bottom you come out the top, and the same is true for left and right. The colors represent different terrains, listed below with their affect on a local city:
Blue - Water/Ocean +2 to food production.
Light Green - Plains +5 to food production.
Dark Green - Forrest +3 to timber production, Halves Missile Attack.
Gray - Mountains +2 to iron production, Cuts Missile Attack by 3.
Yellow - Dessert +1 to gold production.
Aqua - Swamp +1 to cities manna.
White - Neutral (Unowned) Cities.
Dark Blue - Friendly Cities.
Red - Enemy Cities.
Commands Associated with the Global Map:
Click and release on the map and the Local Map appears centered around the square you clicked on.
Click and drag scrolls the Global Map around if the local map is closed, and scrolls the local map if it's open.
