The Systems Alliance is the representative body of Earth and all human colonies in Citadel space. Backed by Earth's most powerful nations, the Alliance has become humanity's military, exploratory, and economic spearhead. While the Alliance is relatively new to the galactic community, it has already made a name for itself, gaining humans an embassy on the Presidium. The Alliance is governed by a parliament based at Arcturus Station, which also serves as the Alliance's capital.
In 2148, a mining team on Mars made perhaps humanity's greatest discovery. After investigating the "Bermuda Triangle-like" reputation of the southern pole, the team unearthed the subterranean ruins of an ancient alien research station, revealing incontrovertible proof of the existence of alien life. Humanity was no longer alone in the universe.

The impact was profound in all areas of human culture, but nowhere more so than religion. New beliefs sprang up overnight such as the Interventionary Evolutionists, who zealously proclaimed the discovery as proof that all human history had been directed and controlled by alien forces. Even established religions struggled to explain extraterrestrial life. Some tried to incorporate this new-found knowledge into their dogma, some remained silent, while a few tried to stubbornly deny the evidence found on Mars.
The news of the discovery dominated the media and raised questions not only about the existence and purpose of humanity, but questions about the aliens themselves. Foremost, were they still out there? While these questions had served to fracture most religions they had a unifying effect in politics. Rather than nations fighting each other over their differences, it was now "us vs. them" and the foundations of a united human front were laid.

Within a year of the discovery, Earth's eighteen largest nations had drafted and ratified the Systems Alliance charter, establishing a representative political body to expand and defend human territory. Shortly thereafter, the various nations of Earth pooled their military resources to create the Systems Alliance Military. The same year, 2149, the Alliance discovered the Sol system's mass relay orbiting Pluto, previously thought to be a moon, Charon. The Charon Relay propelled them into space and the reach of humanity grew quickly.