Thousands of years in the future, the human race has scattered throughout the galaxy, populating multiple planets ruled by aristocratic Houses who themselves answer to the galaxy's Imperial family Corrino. Key is the control of the desert planet Arrakis, the only source of the valuable spice melange, which gives those who ingest it extended life and prescient awareness. Melange is crucial as it enables space travel, which in turn is monopolized by the Spacing Guild; its Navigators use the spice to safely plot a course for the Guild ships via prescience using "foldspace" technology, which allows instantaneous travel to anywhere in the galaxy.The spice is also crucial to the powerful matriarchal order called the Bene Gesserit. The secretive Bene Gesserit, often referred to as "witches", possess mental and physical powers developed through a combination of thousands of generations of genetic selection and years of physical and mental conditioning. When a Bene Gesserit acolyte becomes a full Reverend Mother by undergoing a massive overdose of specific narcotics (called The Agony), she gains access to her "ancestral memories" — the complete life experiences of all her female ancestors back to the point of conception. Only women have been able to survive the transformation. However, the Bene Gesserit have a secret, centuries-old breeding program to create a prescient superhuman — and male equivalent to a Reverend Mother—called the Kwisatz Haderach, who would not only be able to survive “The Agony”, but whose “organic mental powers would bridge space and time”.
The planet Arrakis itself is completely covered in a desert ecosystem, hostile to most organic life. It is also sparsely settled by a human population of native Fremen tribes. Tribal leaders are selected by defeating the former leader in combat. The Fremen also have complex rituals and systems focusing on the value and conservation of water on their arid planet. They conserve the water distilled from their dead, consider spitting an honorable greeting, and value tears as the greatest gift one can give to the dead. Their culture also revolves around the spice, which is created as part of the life cycle of the giant sandworms who dominate the deserts. Bene Gesserit missionary efforts have implanted a belief in a male Messiah who will one day come and transform Arrakis to a world more habitable to humans