From the Back of the Book:
THE HORDE GATHERS
In the Darkness, in the gaps and cracks, in the forest, the cavern, the swamp, at the edge of the campfire's dwindling glow, they dwell...
Ultimate Bestiary: Revenge of the Horde presents a variety of the classic monstrous races, including gnolls, goblins, kobolds, orcs, and trolls, fleshing out their cultures, habits and habitats, and introducing a wealth of stat blocks to challenge your players from level one to the end of their adventuring careers.
So venture beyond the light of your fire, but beware, for here there be monsters.