The Abandoned Realms

The gods are silent and the world is in decay. Thousands of years ago a great calamity happened unknown in nature and scale. The ancients were unprepared and their empires fell. Slowly the people rebuilt but with out the gods things have changed. Magic once common has become rare and valuable, with those who practice it always on the path to losing their magical abilities. The clerics and paladins must make user of what little energies the gods have left to perform miricles which take their toll on the body. What has happened to the gods? What was the cataclysm? How can the people of this world hope to rebuild?