Campaign Classics is a series of usually historical books from Iron Crown Enterprises which provide additional material for campaign settings for Rolemaster and Fantasy Hero. However, much of the material could be converted to other role-playing systems.
The Campaign Classic titles include Mythic Egypt, Mythic Greece: The Age of Heroes, Pirates, Robin Hood the Role Playing Campaign, and Vikings.
The Genre Books are a very similar group of books dealing with similar topics.
The Genre Book titles include Dark Space, Outlaw, Time Riders, At Rapier's Point, Arabian Nights, Black Ops, Pulp Adventures, and Shades of Darkness.