Foundation — Isaac Asimov

For twelve thousand years the Galactic Empire had ruled supreme. Now it was dying. But only Hari Seldon, creator of the revolutionary science of psychohistory, could see into the future--a dark age of ignorance, barbarism, and warfare that would last thirty thousand years. To preserve knowledge and save mankind, Seldon gathered the best minds in the Empire--both scientists and scholars--and brought them to a bleak planet at the edge of the Galaxy to serve as a beacon of hope for future generations. He called his sanctuary the Foundation.

But soon the fledgling Foundation found itself at the mercy of corrupt warlords rising in the wake of the receding Empire. Mankind's last best hope was faced with an agonizing choice: Submit to the barbarians and be overrun--or fight them and be destroyed.