The galaxy

The galaxy was one of the billions of galaxies that existed in the universe, as well as the only galaxy directly accessible by the time of the Galactic Empire. Composed of some four hundred billion stars in a disk 120,000 light-years in diameter, this galaxy was home to between five and twenty million sentient species. Over one hundred trillion sentient beings lived in one billion star systems in this galaxy, and interacted with each other through travel, diplomacy, trade, politics, and war. In historical memory, this galaxy had been ruled by the Galactic Federation, the Galactic Empire, and various smaller factions, including the New Republic.

It was divided into several regions.

Deep Core
At the very heart of the galaxy, the Deep Core (also known as the Core Systems) was a region that spanned seven thousand light years, and contained roughly 30 billion stars. Due to the gravitational pull of the vast number of stars, as well as a massive black hole at the center, local space-time was severely warped, making hyperspace travel difficult at best. For millennia, only the fringes of the Deep Core closest to the Core Worlds, within a mathematically defined boundary known as the Horizon, had been settled. The region was known for its fierce loyalty to the Galactic Empire and was home to the summer retreats of many high nobles.

Core Worlds
The Core Worlds was an ancient region bordering the outlying areas of the Deep Core, and included some of the most prestigious, well-developed, well-known, and heavily populated planets in the galaxy. The Galactic Federation and subsequently all galaxy-wide governments were born in the Core Worlds and spread out over the galaxy. During both the time of the Federation and Empire, Coruscant, a major core world, was the Galactic Capital. The region of the Core Worlds known as the Tetrahedron became the cradle of the early Federation, and simultaneously scouts discovered the Perlemian Trade Route and the Corellian Run emanating from Coruscant, creating a region known as the Arrowhead containing the ancient worlds of Alsakan, Anaxes, Basilisk and Ixtlar. Colonization created a semi-circular ring extending south as far as Abregado-rae, often considered the cream of the Core Worlds, while subsequent centuries create a second ring to the galactic west, though these worlds, disparaged as "the Negs" for their negative-digit galactic coordinates, were looked down upon by the rest of the Core. The Core's natural wealth was buoyed by the farming worlds of the Agricultural Circuit, the semi-independent colonies of the Illodia sector, the Bormea/Darpa Corridor, the manufacturing planets of the Humbarine sector, and the military shipyards of the Kuat sector.

Colonies
The Colonies, so named because it was among the first areas outside the Core to be colonized, contained many of the galaxy's wealthiest worlds and prided itself on being the galaxy's economic engine. Worlds here were typically heavily populated, industrialized, and cultured, and the region was considered the meeting point of Core wealth and Rim raw materials. The Colonies, forming the tip of the Slice, came to include many of the galaxy's oldest manufacturing worlds, including Balmorra, Commenor and Neimoidia. Subsequent colonization produced the shipyards of Loronar, the urbanized worlds of the Pencael system, and the young worlds of Yabol Opa with its great university, the fortress world of Raithal, and the farm worlds of the Delle system.

Inner Rim
The Inner Rim was a region of the galaxy between the Colonies and the Expansion Region. It was originally just called "The Rim", as it was expected to be the farthest extent of the known galaxy for centuries, but the Expanded Rim (later renamed the Expansion Region) was opened within a hundred years of the Inner Rim being settled during the Golden Age of the Federation. Inner Rimmers tended to see themselves as being part of the Core and looked disdainfully upon the "outer galaxy," but were known to resent and envy the greater wealth and history of the Core Worlds. The region had minimal cultural influence and had few truly notable planets beyond the ecumenopolis of Denon and the medical worlds of Manaan and Thyferra. As the bridge between the Core and the Rim, the Inner Rim held great strategic value, and during both the Clone Wars and the Great Interstellar War, brutal battles were fought over the region.

Expansion Region
The Expansion Region began as an experiment in corporate-controlled worlds, known as the Exploitation Region, with powerful corporations exploiting and profiting heavily from the planets for their raw materials, metals and ores. Inhabitants were oppressed while the corporations stripped entire stellar systems along the Corellian Run of all their resources. The damage was so catastrophic that colonization shifted spinward to the Perlemian Trade Route, which was responsible for the conspicuous northern "bulge" of the modern Inner Rim's border. Colonization resumed during the Golden Age of the Federation, but ancient conflicts destroyed many of the Expansion Region's worlds in the Slice, shifting colonization west of the Corellian Run, creating a stretch of space known as the 77 sectors that was dominated by Corellians for millennia. This part of the Expansion Region thrived, with the Rimma, Hydia, and Corellian Trade Spine Routes opening up the region and linking worlds like Tynna, the Gran homeworld of Kinyen, and trading planets of the Harrin Trade Corridor. This region's citizens often preferred to think of themselves as being apart from the rest of the luckless Expansion Region, which continued to suffer during the Federation's final millennium.

Mid Rim
With fewer natural resources (and therefore a smaller population) than many neighboring regions, the Mid Rim was a territory where residents worked hard for everything they had. Colonization began as the Expansion Region was settled, and while corporations continued to prefer to exploit that region, homesteading incentives and development grants from Coruscant were instead picked up by religious communes or local political confederations. The Slice in the Mid Rim was colonized slowly over several millennia, following a crosshatching pattern determined by Coruscant, giving rise to an orderly region whose residents had plenty of room to spread out. Corporate exploitation remained in the Expansion Region while lawlessness gravitated to the less-governed Outer Rim Territories, which were opened for colonization at the same time. Consequently, the Mid Rim built up a successful economy based on low-cost manufacturing and agriculture, as the the northern and southern arcs of the Mid Rim came into shape.

Outer Rim Territories
The Outer Rim Territories was the largest region of the galaxy, and the last widely settled expanse before Wild Space and the Unknown Regions. It was strewn with obscure worlds, and rugged, primitive frontier planets. Due to its distance from the Core, government control was historically the weakest in the Outer Rim Territories, and it was the traditional refuge for dissidents, pilgrims and freedom-seekers, but it was also beset by lawlessness, oppression and violence. The worlds of the Outer Rim were immensely varied as a consequence: Eriadu was a prosperous, industrialised megalopolis, and Entralla was a vibrant, Human-dominated spaceport world, but Terminus and Aduba-3 were criminal-run shadowports, and Tatooine was a Hutt-controlled trade depot. The Outer Rim was also dotted with barely-habited worlds like Dagobah, Hoth, Tund and Muskree. Worlds closest to the major super-hyperroutes tended to be the most civilized, but far from these trade links, they tended to be dominated by the Hutts. Mass settlement of large portions of the Outer Rim did not begin until near the collapse of the Federation, when colonists took advantage of the new trade routes of the Hydian, the Rimma, and the Corellian Trade Spine.

Due to its late exploration, the region was mostly free from the control of the Galactic Empire, and was divided among various powers, most notably the New Republic and the Hutt Cartel.

Unknown Regions and Wild Space
Wild Space was the frontier of galactic society, separating the known parts of the galaxy from the Unknown Regions. It was not a formal label, but was applied to the unsettled galactic fringe and other parts of the galaxy with negligible colonization or development. Wild Space by the Imperial Period typically referred to the wispy fringe of the galaxy's eastern disk, as well as the narrow, meandering strip that separated the civilized galaxy from the Unknown Regions. Wild Space differed from the Unknown Regions in that some of Wild Space had been explored, though not extensively, and the findings recorded in official logs; the Unknown Regions remained mysterious. The worlds of Wild Space largely ignored the central government, and were generally peaceful, but many acted as criminal hideaways.

The term "Unknown Regions" referred to those areas that had not been directly surveyed by Federation or Imperial scouts. It was most commonly applied to the less-known parts of the galaxy's western disk, a quadrant stretching roughly between Bakura and the Galactic Empire. However, the term also applied to the galaxy's halo of gas, dust and stars, as well as the satellite galaxies. When the aggregate of all this territory is summed, the Unknown Regions reached nearly triple the size of settled space, but by some calculations, just 15% of the galactic disk's total stellar mass qualified as part of the Unknown Regions. The chunk of the Unknown Regions within the galaxy was a product of the lack of any western analogues to the Perlemian Trade Route and the Corellian Run, and the Federation's early scouts were content to expand into the easier-to-reach territories of the Slice. It later became clear that the route to the west was in fact barred by a tangle of hyperspace disturbances that effectively split the galaxy in half, forming the midline of the galactic barrier that enveloped the galaxy. The barrier to the Unknown Regions was permeable, however, with spacer tales telling of strange ships visiting distant Outer Rim ports like Terminus, hyperdrive mishaps taking ships through the divide, or ancient alien trails allowing access to the region.