From the Publisher:
This supplement features five primitive races for the d20 system. These races are ideal for anyone playing a campaign that involves primitive or Stone Age cultures. The neanderthal and the aborigine are included among these races along with three other unique races that can only be described as "feral." All the races are presented with discussions detailing their racial tendencies on alignment, personality, relations, language, and physical descriptions.
Resilient and strong, the neanderthal is perfect for players interested in playing a barbarian. The aborigine is a unique human sub-race that has a variable size and wilderness affinity. Some are Small like pygmies, while others grow up to 8 feet tall. They also have favored tribal weapons and keen survival skills. The savage enelils, the monstrous grundengars, and the strange phrohiem each possess at least one natural attack (spittle, musk, ankle spurs, etc.), as well as other unique racial characteristics. Furthermore, these three races can serve as unique, new, monsters as well..
These races first appeared in the Primal Codex, back in 2001, and have now been revised and updated to the 3.5 version of the Core Rules. In addition to new abilities, new modifiers and new descriptions, these races also feature 2 new images depicting the savage enelil and the rugged neanderthal.