The Scattering

The Scattering was a major historical event in the chaotic period following the death of Leto Atreides II, the God Emperor. His death brought the breakdown of his empire, severe famine on many worlds, and the introduction of Ixian no ships. It was all part of the Golden Path, Leto's design, triggered by the perceived need to diversify the human race and allow it to evolve. (God Emperor of Dune; Heretics of Dune)

Origin#

Leto II's prescience allowed him to see into both the past and the future, and he believed that ten thousand years of rule by the Faufreluches had left the human race stagnant, so that drastic action was needed for its survival. The entire purpose of the Golden Path was to force humanity to abandon certainty, security, and safety as individual goals and to scatter geographically, technologically, ideologically, and socio politically. (God Emperor of Dune)

During the reign of Leto II humanity was predominantly planet bound and ruled by an iron fist for more than 3,500 years, in stark contrast to the freedoms enjoyed under the Faufreluches. Leto held the Imperium tighter than any ruler before him, including power over the Spacing Guild and space travel that no previous Emperor had managed. Upon his death the long established order disintegrated, humanity rediscovered independence on a vast scale, and the species was free to scatter into the unknown. (God Emperor of Dune; Heretics of Dune)

The Famine Times and Scattering space#

According to Leto's plan, his death was followed by a collapse of political control and of spice supplies, since it would take generations for the spice cycle to reassert itself on the planet then called Rakis. Worlds starved in the chaotic period known as the Famine Times, and the Scattering was the immediate response as refugees fled the anarchy. (God Emperor of Dune; Heretics of Dune)

Many people remained within the boundaries of the Old Imperium, but countless humans departed for uncharted space, never to return. For 1,500 years humanity explored realms beyond the old boundaries, and new groups and cultures evolved. The number of colonized worlds ballooned exponentially. The Bene Gesserit who remained could make only vague guesses at the size of Scattering space, which was theoretically infinite. One clue was that the Lost Ones returning from the Scattering referred to the Old Imperium as the million worlds, implying that Scattering space was several times larger. On the Dune timeline these fifteen centuries are the longest stretch about which the old powers knew almost nothing. (Heretics of Dune)

New powers and the return#

Eventually the Honored Matres developed as a fusion of Bene Gesserit and Fish Speakers, and possibly other groups, who had fled into the Scattering. An aggressive group focused on conquest and domination, they carved out vast territories among the new worlds. Another power that rose was the Lost Tleilaxu, no longer bound even by the pretense of the Great Convention, who pushed genetic manipulation far beyond their Bene Tleilax forebears, splicing human and animal stock to create the feline based Futars and, in the expanded books, the fish based Phibians. The Honored Matres and the Lost Tleilaxu became bitter enemies in wars that spread across Scattering space, and the Tleilaxu refined the Futars expressly to hunt the Matres. (Heretics of Dune; Chapterhouse: Dune; Hunters of Dune)

About 1,500 years after Leto II's death, many of the Lost Ones began to return to the space of the Old Imperium. Chief among them were the Honored Matres, who exterminated the Bene Tleilax and Bene Gesserit wherever they found them. The Bene Gesserit learned that the cause of this return was that the Matres were fleeing an even more powerful adversary they had encountered, alluded to only as the Enemy, which had made extensive use of biological warfare against which the Matres no longer had defenses. (Heretics of Dune; Chapterhouse: Dune)