The Systems Alliance was the representative body of Earth and all human colonies in Citadel space. The Alliance was governed by a parliament based at Arcturus Station, the station also served as the Alliance's capital.
In 2148 CE, a human mining team discovered alien technology on Mars. Soon after, they discovered the Charon mass relay. The Alliance military began expanding until they were attacked by a group of turians, as they deemed the humans were breaking the law. This began the First Contact War, a short war that the Council intervened in. The Alliance gained more leadership roles on Earth after the First Contact War.
The Alliance had several different sections in society, two being the Alliance Navy and the Alliance Marines.