Mars

Fourth planet from Sol.
The Red planet was the first to birth life in the Sol system, and the first to be ravaged by its inhabitants. Native Borian technological prowess resulted in the catastrophic destruction of their atmosphere, which subsequently destroyed the biosphere. The devastated Borians, driven underground, developed machines to perform a wide variety of tasks. When the Androids developed sentience, they worked amiably with their progenitors to create vast habitable space underground, and began transforming the surface to a livable state. This was the state they first met human explorers, and began working together. Joint experimental attempts to modify Borian and Human phenotypes to survive in harsher conditions resulting in fractionization, and the creation of the Spartan species and faction.
Historically, the Central Mars government has maintained control for the better part of a millenium. Their iron grip over the natives is largely benevolent, but absolute. Over time rebel factions have grown (and been crushed), due to the same heavy-handed tactics.
Native Species: Borian 
Forged Species: Androids  Spartan 
Immigrant Species: Human Ogron