This campaign setting is based on Gygax's classic campaign (Greyhawk) but renamed as he no longer owns the rights to it's original name.
This book is currently out of print as after Gary Gygax' death in March, 2008, all of his intellectual property was removed from Troll Lord Games by a new company Gygax Games which has stated it's intention to reprint this and his other works.
From the back of the book:
The book you hold in your hands is the Setting for the famed Castle Zagyg, the monstrous dungeons of which are detailed in the forthcoming six volumes of this series.
This book consists of the East Mark, which includes the town of Yggsburgh and its Environs, the town of Garham and 60 different geographic locals, each with their own peculiarities and adventures.
The map charts over 1500 square miles of adventuring terrain, allowing the inclusion of Yggsburgh and Environs into almost and fantasy campaign setting. Each geographic locale has one or more adventures associated with it, offering hundreds of different plots, themes and escapades, which the players can take their characters on.
The book includes:
A double sided 24" x 30" fold-out map of the East Mark and Yggsburgh.
Nine Interior Maps of Points of Interest
600+ Non-Player Characters
30+ Random Encounter and Event Tables
50+ Random Encounters
Orders of Battle for everything from Goblins to Knights
New Monsters, Magic Items & Spells for Castles & Crusades