From the preview:
Dawn of Rebellion, the first ever sourcebook of its kind, brings you to the era of the Galactic Civil War before the events of Rogue One™ and A New Hope™, focusing on the tension, strife, and fear encouraged by the Galactic Empire at the height of its power. This is an era where despair is prevalent and the future dark, except for a few unique individuals who carry hope like a torch against the darkness, a torch that would become the spark that ultimately lights the flames of rebellion, war, and freedom.
This book provides players with a wealth of new equipment, specializations, and races to paint this vibrant and dangerous galaxy in stark and stunning detail. But where Dawn of Rebellion truly shines as an era sourcebook is in its service of setting the stage for encounters, sessions, and entire campaigns in a time when the Empire is at its strongest. That is not to mean every campaign that makes use of this book will have the fall of the Emperor as its goal; instead, we can see how Star Wars™: Edge of the Empire, Star Wars™: Age of Rebellion, and Star Wars™: Force and Destiny might approach the same story element from unique angles, and how Game Masters can present these angles to their players.
As an example, let’s use one of the independent organizations described in Dawn of Rebellion, the Broken Horn Syndicate.