The World of Mythosa

From the introduction:

The setting information presented here details a land area of roughly four million square miles, slightly larger than Europe and about a third larger than the contiguous United States. Most of this territory is wilderness, some of which had been settled at one time or another but presently is abandoned due to wars, disease, and other calamities. Having been devastated by a magical conflict known as the Thaumaturgical Wars, the population of humanity and its ilk is scattered, with most people living within 50-100 miles of a coast. Overland travel is dangerous, and lawlessness is the norm.