The Foundation:
The premise of the series is that the mathematician Hari Seldon spent his life developing a branch of mathematics known as psychohistory, a concept of mathematical sociology. Using the laws of mass action, it can predict the future, but only on a large scale. Seldon foresees the imminent fall of the Galactic Empire, which encompasses the entire Milky Way, and a dark age lasting 30,000 years before a second great empire arises. Seldon's calculations also show there is a way to limit this interregnum to just one thousand years. To ensure the more favorable outcome and reduce human misery during the intervening period, Seldon creates the Foundation – a group of talented artisans and engineers positioned at the twinned extreme ends of the galaxy – to preserve and expand on humanity's collective knowledge, and thus become the foundation for the accelerated resurgence of this new galactic empire.
Note that the predictions are only on the GRAND scale…hence the timeframe constantly changing and needing microadjustment.