The Koprulu sector—nicknamed the Terran Sector— is a sector in space colonized by terrans in the shadow of protoss space. It is situated on the galactic fringe of the Milky Way, sixty thousand light years from Earth. During the Guild Wars, the sector was divided into at least five zones. Most of its planets are inhospitable. Still, the sector offers a vast range of foodstuffs.
It appears that, in earlier times, the Koprulu Sector was inhabited - or at least graced - by alien species, given the prevalence of lifeforms that appear to have been formed artificially. But by the time of terran settlement, while the Koprulu Sector featured an extensive range of flora and fauna, no sentient species inhabited it.
When the Nagglfar, the Argo, the Sarengo and the Reagan ventured into the sector, they crash-landed on Tarsonis, Moria and Umoja. Sixty years later, second-generation subwarp engines developed on Tarsonis allowed the colonies to make contact with one another. Tarsonian fleets continued to explore the sector, founding prosperous colonies on Korhal, Tyrador VIII, Tyrador IX, Brontes, Dylar IV, Chau Sara and Mar Sara. These colonies founded the Terran Confederacy.
The Morians had benefitted from having the largest resource mining operations in the sector. Wanting to maximize their ability to drain the resources from the numerous worlds within the sector, as well as fearing that the Confederacy might attempt to move in and use its military strength to regulate their lucrative operations, the Morian Mining Coalition and the Kelanis Shipping Guild merged to form the Kel-Morian Combine. Tensions rose between the Confederacy and the Combine leading to the outbreak of the Guild Wars in 2485.
The Guild Wars were fought on Char, Sonyan, Artesia Prime and Turaxis II. The conflict ended with the Confederacy "negotiating" peace with the Combine in 2489. In the final analysis, the wars assured the Confederacy's supremacy in the sector, which would be unchallenged for the next decade.
In 2499, the zerg infested Chau Sara, Mar Sara, Brontes, and Dylar IV. On December 8, the Koprulu Expeditionary Force incinerated Chau Sara from orbit. The protoss would proceed to do likewise with Mar Sara and Antiga Prime. The fall of Tarsonis resulted in the collapse of the Confederacy in 2500. Arcturus Mengsk formed the Terran Dominion, uniting the sector under one sovereign rule for the first time.
During the Brood War, the United Earth Directorate took control over the sector by sending an expeditionary fleet which occupied Korhal and enslaved the new Overmind. However, their domination of the sector was brief. The zerg under Sarah Kerrigan drove the UED from Korhal and used Dark Prelate Zeratul to kill the Overmind.
For the next four years, Kerrigan was the dominant force in the sector. In 2504, she launched a full-scale invasion of terran space. The invasion was stopped when Raynor's Raiders and half the Dominion Fleet invaded Char. Commander Jim Raynor and General Horace Warfield used a xel'naga artifact to make Kerrigan human again, causing her broods to scatter throughout the sector. Kerrigan rebuilt the Swarm and, with Raynor's help, killed Mengsk before departing to face Amon.