The sphere of space within 50 parsecs of Terra is colloquially referred to as the Solomani Sphere. From 1002 to 1130 it was divided politically between the Third Imperium and Solomani Confederation, and was the focus of the latter's political activity as well those of adherents to the Solomani Cause.
The Solomani Sphere is the colloquial name of a sphere of space centered on Terra that is roughly 50 parsecs in radius and that was formerly part of the Third Imperium. It impinges on the Aslan Hierate to spinward and the Hive Federation to trailing; worlds considered formally under the control of those states are not considered part of the Solomani Sphere (for example, Kusyu, the Aslan homeworld, would be just barely within the Sphere by a strict astrographic definition). In addition to Solomani and other groups of humaniti, the Sphere is home to Minor Non-Human Races, most notably the Vegans, who make up the majority of the population on several dozen worlds near Muan Gwi.
For approximately four centuries the worlds in the Sphere were part of the Third Imperium; after the Solomani Rim War political control was split between the Imperium and the Solomani Confederation. This situation persisted until the Collapse in 1130, when large-scale interstellar states were destroyed due to Virus.
The preponderance of Solomani-descended humans reside in the Sphere; the portion to coreward of Terra has more Vilani influence due to its former membership in the First Imperium. The rimward regions were settled by colonization efforts by the Terran Confederation and various successors, and as a result the humans there are almost totally Solomani in a genetic sense. The Sphere is also the center of Solomani culture, such as it is, promoting ideals such as individuality, cultural diversity, and innovation, as well as belief in the Solomani Cause.
History & Background (Dossier)
Solomanist factions in the Imperial court after the Civil War were alienated by Emperor Zhakirov's marriage in 679 to Antiama Shiishuginsa, a Vilani noblewoman whose family controlled Zirunkariish. To quell dissent in the court, in 704 Zhakirov's daughter Margaret I designated that part of the Imperium in a sphere 50 parsecs in radius centered on Terra the Solomani Autonomous Region, granting a certain amount of regional independence to the Solomanists while nominally maintaining sovereignty (for example, Imperial taxation continued). This region was colloquially called the Solomani Sphere.
The Solomani Autonomous Region was dominated politically by adherents of the Solomani Cause, who believed Solomani to be naturally superior to both other human groups and to nonhumans. Colonization efforts within the Sphere reserved new worlds for Solomani only. In 871, the regional government reorganized and started calling itself the Solomani Confederation. The Imperium did not make any major efforts to regain power in the region until the mid-900s, in response to appeals by worlds with nonhuman majorities in the Sphere protesting chauvinistic treatment by the Confederation government. Margaret II formally declared in 940 that Terra would be reintegrated into the Imperium in 950, but forty more years of efforts by the Imperium to reassert itself were stymied by the Confederation government.
The Solomani Rim War began in 990 with the Imperial objective of eradicating the Confederation government, but the Solomani military tenaciously resisted them. It was twelve years before the Imperium, with great difficulty, captured Terra in 1002 and offered an armistice, which was accepted. The Confederation relocated its seat of government to Home in Aldebaran Sector, and a wedge-shaped volume of the Sphere extending to coreward from Terra came under direct Imperial administration. The Vegan worlds in that volume were organized as the Vegan Autonomous District, and served as the anchor of Imperial power there (Muan Gwi was the seat of the Archduke of the Domain of Sol).
The Imperium never formally recognized the Confederation as independent, nor did the two powers ever sign a formal peace treaty. A state of cold war existed from 1002 through 1117, when news of the Rebellion in the Imperium reached the Solomani. Seeing a chance to recapture their lost territory in the Sphere, the Confederation launched an invasion of Imperial space, recapturing Terra and making major advances in Solomani Rim and Old Expanses sectors. However, they were held off from making further gains by the military forces of Craig, Lucan, and Margaret, uncoordinated though the latter were. Both the main body of the Third Imperium and the Solomani Confederation were destroyed as interstellar states by Virus in 1130.