Welcome to reality on the other side of the rift, set in the world known as the Abode. Rara Avis campaign revolves around the adventures and exploits of the adventuring fraternity know as Rara Avis, beginning in the Nentir Vale. Play takes place approximately one hundred years after the Great Desecration that virtually ended the Nerath Empire and ninety years after the Bloodspear Horde overran the vale nearly destroying everything.
After that, take a look at your wiki. There is some more helpful info there