A YJA Moment - The Imperium

 With the emergence of the Spacing Guild and Space Fold technology, the Core Worlds expanded, and great Dynasties began to vie for control of the galaxy.  Families like the Atreides from Caladan, the Corrino of Kaitain, the Cyrann of Kobol, the Harkonnen of Giedi Prime, and the Organa from Alderaan fought with each other for land and resources.

When the machines created by the Cyrann revolted against their creators, the Dynasties came together to fight them.  The Cylon War unified the Core Worlds and under the Corrino they were forged into a new alliance. This alliance would eventually become known as the Old Empire, the Old Imperium, or simply the Imperium.

The Imperium lasted for thousands of years, their rule uncontested by any other force in the galaxy. It was full of powerful forces - Noble Houses made up of the former Dynasties, the Navigators of the Spacing Guild, the economic might of CHOAM, and the potent psychic abilities of the Bene Gesserit. For most of this time, they were ruled by House Corrino and his dreaded troops, the Sardaukar.

But an Emperor made the mistake of allowing a House feud to involve Arrakis, the desert world that held Melange, the drug which allowed the Navigators to function.  The Dune War would result in the fall of House Corrino and the ascendancy of House Atreides to the Golden Lion Throne. The new Emperor made reforms and changed the Imperium forever.

The last of the Imperial line was a near-omnipotent psychic known as the God-Emperor. Upon his death, the Imperium fractured, and the Noble Houses resumed warring against each other. During the battle, the planet of Arrakis was lost and soon space travel became far less frequent due to the rationing of the last reserves of Melange.

When the planet Corellia discovered Hyperdrive technology, the monopoly of the Spacing Guild was finally broken. Though slower than Space Folds, Hyperdrives were cheaper to produce, could navigate by computers, and was powered by easilier acquired fuel. The hyperdrive would allow a new interplanetary government, the Galactic Republic to sweep through the core worlds, assimilating the last vestiges of the Imperium.