Astrography Astrography was the study of locations and variations in natural and artificial phenomena in the galaxy . In other words , it was the science of mapping interstellar space . Astrography of the galaxy . The galaxy was of SBa and it was 120 , 000 light year s across . The Astrographic Survey Institute was responsible for much mapping after the Galactic Civil War . There were approximately 400 billion stars and around half of these had planets that could support life . 10 % of those developed life , while sentient life developed in 1 / 1000 of those ( about 20 million ) . The galaxy was divided into several regions , listed here in ascending order of distance from the core . These regions were further divided into various sectors , systems , and planets . Deep Core . At the very heart of the galaxy , the Deep Core ( a . k . a . Core Systems ) was a small region that hid unusual worlds . Due to the gravitational pull of the vast number of stars , local space - time was severely warped , making hyperspace travel difficult at best . The region was thought to be inaccessible until Emperor Palpatine found several safe hyperlanes into the region . The area remained an Imperial stronghold almost twenty years after the Battle of Endor . Core Worlds . An ancient region bordering the outlying areas of the Deep Core , the Core Worlds were some of the most prestigious , well - developed , well - known , and heavily populated planets in the galaxy . The Core Worlds were the original areas of Human occupation . The Galactic Republic and subsequently all galaxy - wide governments were born in the Core Worlds and spread out over the galaxy . Humans are theorized to have originated from this region . Colonies . The Colonies was the name given to a region of the galaxy between the Core Worlds and the Inner Rim . It was among the first areas outside the Core to be colonized , and the worlds there were typically heavily populated and industrialized . During its reign , the Galactic Empire was very forceful in controlling the Colonies , and as a result , the New Republic gained support quickly there . 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 . During the reign of Palpatine , the Galactic Empire ruthlessly controlled the Inner Rim . Rather than rebel , many residents chose to flee to the Outer Rim Territories . After the Battle of Endor , the Empire , despite its unpopularity , held the region far longer than expected ; many later resented the New Republic ' s sluggishness in liberating the region . Many worlds , despite joining the New Republic , were openly afraid that the government was not strong enough to maintain power . Their concerns were borne out following the return of Palpatine , when the Empire reclaimed most of the Inner Rim . Expansion Region . The Expansion Region was an experiment in corporate - controlled worlds , 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 of all their resources . Eventually civil unrest spread from system to system . The Galactic Republic eventually took control of the system , due to mounting pressure from its denizens , by limiting or evicting corporate interests . Expansion Region worlds continued to be producers of raw materials and ores . However , most natural resources had been exhausted by the Imperial era . 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 . Several planets built up impressive economies , and pirate raiders often hid in the relatively unexplored spaces far from major trade routes . Outer Rim . The Outer Rim Territories was 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 , the region was home to many supporters of the Rebel Alliance . The Empire ' s Grand Moff Wilhuff Tarkin was assigned the difficult task of bringing the entire Outer Rim in line . Tingel Arm . The Tingel Arm was an exterior spiral arm of the galaxy , located along the edge of the Outer Rim . It contained the Corporate Sector Authority , a political entity which was semi - independent of the Galactic Republic and the Galactic Empire . Under the Galactic Empire , the sector expanded from a few hundred to thirty thousand systems . Beyond the Outer Rim . There were several sectors beyond the Outer Rim , on various arms of the galaxy . Wild Space . Wild Space was the frontier of galactic society , separating the known parts of the galaxy from the Unknown Regions . One of Palpatine ' s last acts was to open up much of the region to more extensive exploration . Wild Space differed from the Unknown Regions in that some of Wild Space was explored , though not extensively ; the Unknown Regions remained completely mysterious . Unknown Regions . The term " Unknown Regions " most commonly referred to the large , unexplored region ( which some interpreted to have been outside the plane of the galactic disk ) between Bakura and the Imperial Remnant , which was largely dominated by the Chiss Ascendancy . The Unknown Regions comprised only a few billion stars , out of a galactic total of 400 billion . For reasons yet to be demonstrated there was a lack of reliable hyperspace routes through the region . The " Unknown Regions " designation included uncharted areas in dense nebulae , , and the . Traffic Routes . Various established " ways " such as hyperlane s passed through the sectors . These routes were explored and established by spacers known as hyperspace explorers ( like Gav Daragon and Aitro Koornacht ) . Astromech droids had the responsibility of guiding spaceships through these routes .