RIFTS Aftermath is probably the most thorough description of the empires, kingdoms, places, and many of the various factions all across RIFTS Earth in a single book. While this book describes all of this following the post Siege on Tolkeen meta-plot, there is other world information here that is not found anywhere else. Although, if you need very detailed information about RIFTS England, your best overall bet is still to pick up the RIFTS England book. RIFTS Aftermath updates the general world information to the year 109 PA in the RIFTS setting. Very useful, and even moreso if you follow the world events of the Siege on Tolkeen.
[4 of 5 Stars!]