Moria is the capital world of the Kel-Morian Combine. This red, mineral-rich planet was one of the first three planets originally settled by the Terrans, along with Tarsonis and Umoja. Separated from its sister worlds by vast distances, Moria developed in isolation for sixty years until contact was made with exploration ships from Tarsonis. Communications and trade were opened up between the three worlds, though efforts by Tarsonis to unite their worlds under one government were resisted by the Morians.
With the formation of the Terran Confederacy, Moria began to fear the Confederacy might attempt to move in and regulate their lucrative operations. In response, two powerful organizations, the Kelanis Guild and the Morian Mining Coalition, formed the Kel-Morian Combine, a shady, corporate partnership led by Gen Mah Sakai that promised military aid to any Mining Guild oppressed by the Confederates. The resulting increase in tension led to the Guild Wars between the Confederates and Combine, which was resolved after fours years of fighting by a "negotiated" peace settlement. The Combine retained its autonomy but lost almost all of its Mining Guilds to Confederate control.
When the Confederacy was overthrown and replaced by the Terran Dominion, Moria rallied to Mengsk's banner and joined the new administration. The invasion of the United Earth Directorate during the Brood War weakened Dominion power, allowing Moria to break away and become independent again. Moria also came under attack when the Zerg raided the planet for resources for Kerrigan's planned invasion of Korhal.
As of StarCraft II: Wings of Liberty Moria is still an independent power, spending its still-vast resources preparing for the inevitable war with the Dominion, the Zerg, or both.
Read more about this topic: Koprulu Sector