This book describes the various factions that make up the Periphery: Magistracy of Canopus, Taurian Concordat, Marian Hegemony, Outworlds Alliance, Circinus Federation, the Lesser Periphery States, Bandit Kingdoms and the Deep Periphery. This sourcebook describes the history, military doctrine, traditions and tactics of each Periphery faction, plus special rules that reflect the exclusive capabilities of each Periphery regiment, as well as new weapons and BattleMechs unique to the Periphery.