A long time ago in a galaxy far, far away... the Citadel, the political, cultural and financial capital of the universe, wasn't even discovered yet. This era is called the Pre-Council Era. The earliest event in Mass Effect history is the disabling of a Reaper, a highly advanced, organic, sentient starship, by an unknown race 37,000,000 years before the discovery of the Citadel. This derelict reaper began orbiting Mnemosyne, thought to be dead.

A few million years later, the only spacefaring race of their time, the Protheans, established a vast empire spanning across the galaxy. Using what was though to be their own technology and the Mass Relays, the Protheans linked together their civilization before mysteriously disappearing in 48,000 BCE.

Fast forward 48,000 years later and the Asari, while experimenting with Mass Relay technology, stumble upon the Citadel in the Serpent Nebula. This marks the start of the Council Era and the Galactic Standard timeline.

Important Facts:

Derelict Reaper

  • 37,000,000 BCE: 37 million years before the founding of the Citadel Council, an unknown race fired off a giant mass accelerator round of devastating power. This round ripped through a Reaper, a highly advanced organic, sentient starship.

Protheans Vanish

  • 48,000 BCE: The Protheans' reach spans countless galaxies and planets and their empire grows to enormous proportions before they mysteriously vanish. The Mass Relays and the Citadel is believed to be leftover Prothean technology.

Krogan Holocaust

  • 1900 BCE: The Krogans, native to Tuchanka, discover nuclear power. Unfortunately, this spirals out of control and WMDs go off, causing global devastation. As a result, the Krogans fall into a primitive, savage, clan-based society.

Mu Relay Lost

  • 1800 BCE: A supernova explodes, propelling the Mu Relay, the only Mass Relay connected to the Pangaea Expanse. The relay is lost in the abyss of space and the Pangea Expanse is cut off.

Citadel Discovered

  • 580 BCE: While experimenting with what was thought to be Prothean technology, the Asari start exploring the various Mass Relays and where they lead. Eventually, they stumble upon the Citadel and set up camp. 60 years later, the Salarians find the Citadel and open diplomatic relations with the Asari.