A world whose lands are made up of huge terrain spheres that rotate constantly with most portion underwater. As time passes, the shape of the bodies of water change, landmarks shift inside the new border lines, and mountains tilt to different degrees. Land dwellers are gypsies that can never build anything permanent, and somewhat ironically, the only stable settlements are large structures built at sea.
There are no scrolls in this world, but there are crystals of various sizes, colors and qualities. Every spell has a requirement on the amount and characteristics of crystals that must be held in order for the spell to be cast, crystals which would shatter should the cast be successful. Now picture a land where crystals are scarce except for high concentrations of them in specific spots throughout the land. A number of scenarios could occur, such as benign companies selling the mined valuable for cheap, a region in constant magic-intense war zone, an area of crystals in the quicksand, or an undiscovered patch next to a town...
What to export or import....
Fabric: wool, linnen, silk...
Wood: raw-material, furniture
Metals: iron, gold, silver, copper...
Wine, beer, mead, spirits...
Animals: horses, sheep, swine, cows...
Coloring-powder (for fabric, ink...)
Raw-material to make fabric: unprocessed wool, linnen, silk...
Glass: Windows, figurines, glasses, raw-material...
Tea (not sure about my spelling here, but I mean the hot drink Englishmen drink instead of coffee!)