Timeline

This is the timeline of the Mass Effect universe. All dates are in BCE (Before Common Era) and CE (Common Era).

Pre-Council Period (48,000 BCE - 520 BCE )
48,000 BCE (Approximate)


 * The Protheans, a galaxy-wide civilization linked by the mass relay network, mysteriously vanish, leaving only ruins and artifacts behind. Archaeologists will later believe that they were destroyed in a cataclysm.

1900 BCE (Approximate)


 * Tuchanka, the krogan homeworld, enters the nuclear age. In a global conflict, weapons of mass destruction are released, triggering a nuclear winter.  In the resulting devastation, krogan society devolves into a collection of warring clans.

1800 BCE (Approximate)


 * A supernova propels one of the mass relays out of its position. The dense nebula formed by the supernova means the relay's position is effectively lost.

580 BCE


 * After developing faster-than-light spacefaring capabilities based upon Prothean technology, the asari begin to explore the mass relay network, and eventually discover the huge Citadel space station at a hub of many mass relays.

520 BCE


 * The salarians discover the Citadel and open diplomatic relations with the asari.

Early Council Period (500 BCE - 2100 CE)
500 BCE


 * The Citadel Council is formed. The asari and salarians together colonize the Citadel and establish it as a center of the galactic community, led by the Council. This year is also known as 0 GS, the beginning of the Galactic Standard (GS) timeline.


 * As a gesture of openness with their new asari allies, the Salarian Union opens the records of the League of One. Under threat, the League responds by assassinating the whole inner cabinet of the Union; STG operatives then wipe out the League.


 * The turian Unification War begins.

500 BCE (Approximate)


 * The Council races begin expanding the galactic community, opening first contact with other spacefaring races and integrating them into the Citadel. For the next 1200 years, this period of is marked by rapid growth and occasional conflict.


 * First contact is made with the volus although at first they are not permitted a permanent embassy on the Citadel. With their participation, a single galactic currency - the credit - is eventually established, linking all galactic economies.

200 BCE (Exact)


 * The Council agrees to grant the volus the honour of being the first species with an embassy at the Citadel, but not a Council seat.

200 BCE - 1 CE


 * The batarians post an embassy, a century or more after first contact.


 * The asari stumble into the elcor system, and help them to locate and activate their nearest mass relay. "Within one elcor lifetime" they establish a regular trade route to the Citadel and soon post an embassy.


 * First contact is made with the hanar and the quarians. The quarians post an embassy.

1 CE : The Rachni Wars


 * The Citadel Council first encounters the rachni, a species of highly intelligent hive-minded insects. They are discovered when an expedition opens a dormant mass relay to their star systems. The rachni prove to be hostile and begin a war with the rest of the galaxy. The Council cannot negotiate because they cannot contact the rachni queens that live underground on the toxic rachni home worlds.

80 CE (Approximate)


 * The Rachni Wars continue. The salarians transplant the primitive krogan to another world and manipulate them into acting as soldiers for the Citadel Council. The krogan are able to survive the harsh environments of the rachni worlds, and begin a strategy of eradicating queens and eggs.

300 CE


 * The rachni are declared extinct. In gratitude for their aid during the Rachni Wars, the Council grants the krogan a new homeworld. Free of the harsh environment of Tuchanka, the krogan population explodes.

300-700 CE (Approximate)


 * The krogan begin to expand exponentially, colonizing many new worlds. Growing concerns about their expansion lead to the founding of the Special Tactics and Reconnaissance branch of the Citadel.

700 CE : The Krogan Rebellions
 * Krogan warlords leverage veterans of the Rachni Wars to annex territory from others in Citadel space. Eventually the Council demands withdrawal from the asari colony of Lusia, but the krogan refuse.  A pre-emptive strike is made on krogan infrastructures by the Council, using the newly-created Spectres.  The Krogan Rebellions begin.


 * First contact is made with the turians. In response to krogan threats, they declare war.  After the krogan devastate turian colonies with weapons of mass destruction, the turians respond with a salarian-engineered bioweapon, known as the genophage.  The krogan population starts its decline.


 * The turians accept the volus as a client race within the Hierarchy.

800 CE
 * The Krogan Rebellions end. The turians begin to fill the military and peacekeeping niche left by the decimated krogan.


 * The Citadel Conventions are eventually drawn up, in the wake of the conflict.

900 CE


 * The turians are granted a place on the Citadel Council, and their fleet acts as a galactic peacekeeping force.


 * A second wave of expansion begins. Over the next 1200 years, the Citadel makes first contact with many new species and governs over a galactic community that is experiencing peace and prosperity.

1600 CE (Approximate)


 * First sightings are made of the Collectors, from the Omega-4 mass relay in the Terminus Systems. Little is known about this enigmatic race, and most Council races dismiss stories of them as urban legends.

19th Century CE
 * The quarians create the geth for use as laborers and soldiers. In less than a century, the quarians notice that the geth are showing signs of self awareness, and plan to destroy them before they become a menace.

20th Century CE
 * The Geth Wars
 * On the Quarian homeworld, the geth rebel against their quarian masters and, in the resulting war, reduce their creators to a species of space faring nomads aboard the Migrant Fleet. Contrary to expectations, the geth do not venture outside the former quarian star systems, instead isolating themselves from the rest of the galaxy behind the Perseus Veil. In punishment for their actions, the Citadel Council closes the quarian embassy on the Citadel.

Contemporary Period (2069 CE - 2155 CE)
2069 CE


 * July 20: Armstrong Outpost at Shackleton Crater is formally founded as the first human settlement on Luna, on the 100th anniversary of the first lunar landing.

2077 CE


 * Liara T'Soni is born to Matriarch Benezia and an unknown asari.

2103 CE


 * The European Space Agency's Lowell City in Eos Chasma becomes the first permanent human settlement on Mars.

2137 CE


 * David Anderson is born.


 * Ashland Energy Corporation demonstrates helium-3 fuel extraction from the atmosphere of Saturn.

2139 CE


 * Saren Arterius is born.


 * Kahlee Sanders is born.

2142 CE


 * Construction of Gagarin Station (Jump Zero) begins beyond the orbit of Pluto.

2147 CE


 * Trace amounts of element zero are discovered on Mars.

2148 CE


 * Humanity discovers a small cache of highly advanced Prothean technology hidden deep beneath the surface of Mars on the south polar region of Promethei Planum. Building on the remnants of this long extinct race, humans quickly explore the science of mass effect fields, leading to the development of faster than light travel and beginning detailed exploration of the solar system.

2149 CE


 * Following information from the translated data cache on Mars, humans discover that Charon, Pluto's moon, is actually a massive piece of dormant Prothean technology - a mass relay - encased in ice.


 * Once activated, Jon Grissom leads the first team of explorers through the relay. They discover that the Charon Relay allows instantaneous travel across thousands of light-years to a synchronized mass relay in another part of the galaxy.


 * The Systems Alliance charter is signed by the eighteen largest nations on Earth. The Alliance soon becomes the military and exploratory spearhead of humanity.

2151 CE


 * To defend its rapidly expanding empire, humanity assembles a massive fleet and begins construction of an enormous military space station at Arcturus, at the nexus of several key mass relays... even though they have yet to encounter another intelligent space-faring species.


 * An accident at Singapore International Spaceport exposes a human population to dust-form element zero. After his mother is exposed during the accident, Kaidan Alenko is born later that year with biotic potential.

2152 CE


 * The Systems Alliance begins settlement of Earth's first extra-solar colony world, the planet Demeter.


 * Roughly 30% of the children born in Singapore after element zero exposure suffer from cancerous growths.


 * A human colony is founded on Eden Prime.

2153 CE


 * Pallin joins C-Sec.

2154 CE


 * The media on Earth covers a second accident where humans were exposed to element zero.


 * 4.11.2154: Commander Shepard is born.

2155 CE


 * Saren Arterius is promoted to active service in the turian military at the age of 16.


 * The Systems Alliance occupies completed portions of Arcturus Station as a headquarters.

Humanity's Rise (2156 CE - 2179 CE)
2156 CE
 * Arcturus Station is inaugurated.


 * A small number of human children exposed to element zero exhibit minor telekinetic abilities.


 * A mass relay is discovered at Pluto.

2157 CE
 * Pluto's orbit becomes circularized as a result of mass relay operations.


 * David Anderson graduates from OCS with the rank of First Lieutenant.

The First Contact War


 * Humanity makes first contact with another space-faring culture: the turians. Unfortunately, the encounter is far from peaceful. The turians find the human fleet attempting to activate a mass relay, something forbidden in galactic law after the Rachni Wars, and attack. Over the next several months, a brief but tense conflict known on Earth as the First Contact War ensues. David Anderson, newly graduated from the Alliance's elite N7 programme, serves with distinction alongside Jill Dah. Saren's brother is one of the turian casualties. Finally General Williams is forced to surrender the garrison at Shanxi to the turians.


 * Admiral Kastanie Drescher leads the Second Fleet against Shanxi, catching the turians by surprise and evicting them from the planet.


 * The turians gear for a full war against humanity, but this draws the attention of the Citadel Council. The Council intervenes before hostilities escalate further, revealing the existence of the greater galactic community to humanity and brokering a peace between them and the turians.

2158 CE
 * Humans learn potential of biotics. An international effort to track element zero exposures begins. Roughly 10% of exposed children show some sign of biotic ability.


 * April 14: Ashley Williams is born.

2159 CE
 * Saren Arterius becomes the youngest turian to enter the Spectres.

2160 CE
 * Systems Alliance Parliament formed.


 * With the existence of human biotics firmly established, the BAaT programme is set up on Gagarin Station to train potential candidates and develop biotic implants.


 * "Red sand", a biotic drug, is used for the first time.

2161 CE
 * Amid concerns over gene therapy and genetic modifications being misused, the Alliance Parliament passes the Sudham-Wolcott Genetic Heritage Act.

2162 CE
 * Construction of Arcturus Station is completed.


 * A survey team working for a batarian entrepreneur, Edan Had'dah, discovers a mysterious artifact orbiting an unnamed planet near the Perseus Veil.

2163 CE
 * The Alliance secretly begins illegal AI research at a base on Sidon with Dr. Shu Qian as project leader. Lt. Kahlee Sanders is assigned as a tech analyst.


 * First experimental 'L1' biotic implants used in humans.


 * The NDC founds a colony on Noveria.


 * Harkin becomes the first human C-Sec officer.


 * The Alliance begins charting the Voyager Cluster.


 * The Leviathan of Dis disappears, coinciding with the arrival of a batarian dreadnought.


 * Kumun Shol and his army of mercenaries begin excavating the surface of Klencory.


 * A survey team reports strange disturbances in the clouds of Logan. Upon investigation however, the signals disappear.


 * Second generation exposures by humans to element zero are orchestrated by the failure of drive systems over populated areas.

2165 CE
 * Humanity continues to expand, founding more colonies and establishing trade alliances with many of the other species who recognize the authority of the Citadel Council. In 2165, the Council makes official recognition of humanity's growing power and influence in the galactic community. Humanity is granted an embassy on the Citadel, the political and economic heart of the galaxy. Tensions grow between humans and batarians as they compete for territory in the Skyllian Verge.


 * The events of Mass Effect: Revelation occur. After an Alliance research station at Sidon is attacked, David Anderson searches for those responsible alongside Kahlee Sanders, and discovers an Alliance scientist, Dr. Shu Qian, was conducting illegal AI research to unlock the secrets behind a mysterious artifact discovered near the Perseus Veil. Eventually, Anderson is assigned to work with Saren Arterius to track down Dr. Qian and his batarian supporter, Edan Had'dah. However, Saren instead kills both Dr. Qian and Had'dah, blames Anderson for the mission's failure, and uses Dr. Qian's research to search for the artifact himself.

2166 CE


 * A turian mercenary, Commander Vyrnnus, is hired to oversee training at BAaT.


 * The first human colony at Intai'sei is founded.

2167 CE
 * L2 biotic implants first developed and used in humans; Kaidan Alenko is among the first to receive the new implants.

2169 CE
 * Kaidan Alenko accidentally kills Commander Vyrnnus after being provoked. The diplomatic fallout with the turians results in BAaT being shut down.

2170 CE
 * The human colony of Mindoir is attacked by batarian slavers. Many colonists are killed or captured.


 * Another human colony, Yandoa, suffers catastrophic dust-form element zero exposure to its atmosphere when an Eldfell-Ashland Energy ship explodes in orbit. Many children suffer birth defects; thirty-seven biotic children are born, including Gillian Grayson.


 * Biotic training for humans is outsourced to the military, to selected R&D companies, and to renamed divisions of the Conatix Industries.


 * L3 biotic implants are developed after the L2 implants prove to be dangerous.

2171 CE
 * In protest at the Council's refusal to check human expansion in the Skyllian Verge, the batarians close their embassy, withdraw into their home systems, and effectively become a rogue state.

2172 CE
 * 4.11.2172: Shepard enlists in the Alliance military (this date is also Shepard's birthday, see above).

2173 CE
 * A fly-by over the world of Armeni discovers odd surface portrusions. Upon closer inspection, they turn out to be elaborate crypts for the zeioph, a now extinct former space-faring race. Various human universities seek to perform excavation. Council Law forbids this however, and a debate ensures.


 * Terra Firma is involved in a Nashan Stellar Dynamics kickbacks scandal, forcing Inez Simmons (the current party leader) to resign. Charles Saracino becomes the new party leader after his opponent, Claude Menneau, mysteriously vanishes while en route to Shanxi.


 * Risa Uvarsen uses the terrain of Faringor to film the external scenes of the movie Starless.


 * Golo is exiled from the Migrant Fleet for trying to sell quarians to the Collectors.


 * Kaidan Alenko enlists in the Alliance Navy.

2174 CE
 * Ashley Williams finishes high school and enlists in the Alliance military.

2176 CE
 * Batarian-funded pirates and criminals launch a surprise attack on the human colony of Elysium, later known as the Skyllian Blitz. The assault is repulsed by the Alliance Navy and ground teams.


 * The Jon Grissom Academy is commissioned over Elysium, and becomes home to the Alliance's new biotic training program, the Ascension Project.

2177 CE


 * During a recon mission to find a missing colonial pioneer team on Akuze, a unit of fifty Alliance marines is wiped out by thresher maws.

2178 CE
 * The Alliance tracks several pirate FTL exit vectors during the 'Theshaca Raids'. In retaliation for the Skyllian Blitz, the Alliance launches a major offensive against the moon of Torfan and destroys the criminal bases there, mostly populated by batarians. The threat against human colonies from batarian extremists is curtailed.


 * Tali'Zorah nar Rayya’s mother dies after contracting an airborne virus aboard the Migrant Fleet.


 * ExoGeni Corporation announces its decision to settle the world of Feros.

2179 CE
 * A colony on Proteus is founded.

Mass Effect (2183 CE - 2185 CE)
2183 CE
 * Humans and turians collaborate on an engineering project co-founded by the Citadel Council - an experimental frigate with a prototype stealth system, the SSV Normandy. The Normandy is commissioned with Captain Anderson in command. Commander Shepard - now a promising young officer in the Alliance Navy - is assigned as XO.


 * The colonization of Chasca begins.


 * June 17: Ashley sends a response email to her sister.


 * The events of Mass Effect occur. Saren Arterius's attack on Eden Prime is revealed to be part of a larger plan orchestrated by Sovereign, a Reaper seeking to return the rest of its brethren to the galaxy. After suffering a vision from a Prothean Beacon, Commander Shepard and the crew of the SSV Normandy track Saren, uncover the truth behind the Conduit, and defeat Saren and his geth army aboard the Citadel while the Alliance Navy takes on Sovereign. The Citadel Council is irrevocably changed by Shepard's decisions.


 * The events of Bring Down the Sky and Pinnacle Station occur.


 * L4 biotic implants are developed.


 * The events of Mass Effect: Ascension occur. With galactic society still in flux over the changes to the Council and none the wiser as to the true nature of Sovereign or the Citadel and mass relays, Cerberus pushes ahead with plans for both the Ascension Project and the quarian Migrant Fleet, but is foiled by the actions of Kahlee Sanders and Paul Grayson. After an attack by Cerberus forces, the Migrant Fleet changes its conservative policy, sending ships away from the Flotilla to look for new homeworlds or possibly a dormant Reaper.


 * The events of Mass Effect Galaxy occur.


 * The opening events of Mass Effect 2 occur. While on patrol for geth, the SSV Normandy is attacked and destroyed by an unidentified assailant. Commander Shepard dies in the aftermath, but is found and restored to life by Cerberus. Unaware of this, the Systems Alliance officially declares Shepard "killed in action".

2185 CE
 * The events of Mass Effect 2 occur. Commander Shepard is tasked by the Illusive Man to investigate the mysterious disappearances of entire human colonies.