Twenty-one thousand years before this story, eight large shiploads of refugees fled a vast war of destruction, an Armageddon in a distant part of the spiral arm.
They were wise enough to realize that, being human, they carried with them the seeds of future discords and war. And in an effort to avoid those wars becoming megawars, they developed The Sacrament. This was a powerful system of pain-drug-hypnosis conditioning for all the refugees, and for all their descendants forever. It was designed to prevent scientific curiosity and investigation. They also stripped their ships' computers of scientific and technological information that might lead to development of megawar weaponry.
For several years the refugees traveled in hyperspace, emerging from time to time to explore some promising planetary system for a habitable world. Eventually they settled on one they named Iryala.
Over the following millennia, the Iryalans colonized other planets in their sector of the arm, always taking with them the Sacrament and its technicians. Their worlds and progeny remained under the dominion of Iryala, which retained to itself the exclusive manufacture of spacecraft, space drives, and space weaponry.
Despite new worlds, new conditions, new colonies, the Sacrament resulted in a technologically and mentally stagnant culture which increasingly stressed the concept of Standardness. And a shallow view of both past and future, without a great deal more curiosity about history than about the principles of how the universe works.
Each confederated world had its own ingrown interests and focuses, and they were too far flung to be closely ruled. What held them together was the Sacrament, and their dependence on Iryala for technology. Many of the colony worlds never achieved a central planetary authority, but developed autonomous states separated by rivalries and grudges.
The Confederation of Human Worlds, in its various historical formats, had never experienced space warfare. In fact, with one exception, all its wars had been surface wars between states that shared a common world. And in the more distant past, revolts against Iryalan authority.
It hadn't even made a show of force in space for over seven hundred years. Its naval equipment was of inherited designs, modified long millennia earlier to serve police functions rather than fight wars.
During the exodus, long forgotten now, two large groups of refugees had been purged for refusing the Sacrament. They'd been put down on two planets so difficult, survival seemed questionable and civilization impossible. As the Confederation expanded, those two forgotten worlds had been rediscovered. For a long time their primitive peoples were treated as anomalies, and not quite human. One of those planets was Tyss, also known as "Oven." Tyss was so poor that for millennia its only export was superb mercenary regiments, hired by states on worlds without a central planetary government, to help fight their many small wars.
The T'swa—the people of Tyss—had evolved a culture that eventually caught the interest of a small group of Iryalan aristocrats. Now the T'swa had a new export: ideas. And those aristocrats formed the opening wedge in the stagnated culture of the Sacrament. The Confederation began a planned and gradual change, heretical and covert.
Meanwhile the ancient Home Sector had been terribly ravaged by the interstellar war the refugees had fled. Some planets had been literally destroyed, physically disrupted. Others were rendered uninhabitable for most lifeforms. On still others, the environment was sufficiently degraded that the demoralized humans who survived the war did not survive its aftermath.
Only three worlds retained human populations, and technology had died on them all. Eventually one of them, Varatos, reevolved science, redeveloped space flight, and discovered and subjugated the other two. On eight others, the ecology had adjusted sufficiently to be habitable again, and the Vartosi colonized them. The result was an interstellar imperium calling itself the Karghanik Empire.
Exploration had found no further habitable planets in their sector. Their religion accounted for this peculiarity as the will of God—the same God they believed forbade birth control.
Eventually, the worlds of the Empire grew seriously overpopulated. Finally one of its planets, Klestron, sent an expedition years beyond known space. There it encountered and skirmished with the alien Garthids. Later the expedition discovered and took possession of a very minor "trade world" on the periphery of the Confederation. Within months, however, they were driven from it.
But the expedition had broken the ignorance of both human sectors by whetting the appetite of the Empire, while pressing the Confederation to accelerate change.
And disturbing Garthid isolation.