>The desert in Mystara is a magical creation, the result of the weather
magic of Alfheim. The distance between the vikings and the Byzanthium
empire is about the size of half Europe and there were vikings and
Byzanthium empire in RL at the same time. As was a medieval Europe
(Karameikos, or in RL England) and Rennaisance one (Darokin, or in RL
Italy). You would be surprised at the diversity in Europe even over such
a small distance as the 200 km or so between the west coast of the
Netherlands and the border with Germany (especially in the 16th
century).

Pieter Sleijpen<

The magical cause of the desert was a nice after the fact rationalization,
but the fact that it would have had a climactic effect both north and south
was ignored. As well, this still doesn't deal with all the bizarre mountain
ranges and other physical conditions of the world.
Which really doesn't matter as long as whoever uses it has fun.

Samwise