From the text (back cover):
Perilous Lands is a monumental work that details an entire fantasy continent. It is intended to be used as the setting for your Powers and Perils campaign.
The books in Perilous Lands are the Map Book, a Culture Book, and a Site Book. The pages of teh Map Book detail the physical environment, political boundaries and population centers for the continent and its associated islands. Each of its twenty-six, four-color maps connects to those that surround it to provide a strategic maneuver area that can be easily handled in play, while still allowing journeys of epic proportions.
The Culture Book details the past history, population, armed strength, economy, personality, legal system, allies, enemies and common languages for each of more than one hundred cultures. A millenia of the land's recorded history is woven into a comprehensive, epic tapestry that brings it to life.
The Site Book completes the package. Its pages detail more than fifteen areas, with precise details and general information, that the Referee can develop into complete adventures for his world. In addition, it contains special addenda and aids that will help the Referee to use these books in play.