Timeline

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

Prehistoric Times (Unknown BCE - 1,000,000,000 BCE)
The Leviathans dominate the galaxy, enthralling every new sapient race they encounter and protecting them in return for tribute. The Leviathans consider themselves the galaxy's first and only apex race.

After observing that their subservient races create synthetic races who consistently and violently rebel, the Leviathans create an Intelligence to seek a way to permanently preserve organic life. The Intelligence constructs an army of "pawns" to gather genetic information throughout the galaxy.

The Intelligence betrays the Leviathans, using its pawns to slaughter them for their genetic material to create Harbinger, the first Reaper.

Thus begins the cyclical harvest of the galaxy's intelligent organic life by the Reapers, part of a vast experiment conducted by the Intelligence to fulfill its mandate. The Intelligence builds the mass relay network to increase the efficiency of the cycles, allowing galactic civilizations to develop faster and more consistently between harvests.

Pre-Prothean Times (1,000,000,000 BCE - 68,000 BCE)
1,000,000,000 BCE

The Leviathan of Dis, a Reaper, is killed by the Leviathans. Its corpse comes to rest on the planet Jartar and remains undisturbed for nearly one billion years.

37,000,000 BCE

An unknown spacefaring race fires a mass accelerator round at a Reaper near the planet Mnemosyne. The round penetrates the Reaper, disabling it, and continues moving through space, eventually striking the planet Klendagon and creating the geological feature there known as the Great Rift Valley.

298,000 BCE

The ancient arthenn race flourish in the Zelene system, living on the planet Helyme until being destroyed in an unknown event that wiped out all complex life on the planet. They also maintained a presence on other planets in the system including Epho, which bears the scars of an ancient orbital bombardment, and Gaelon, which may have been mined for helium-3.

125,000 BCE

Ancient spacefaring races called the thoi'han and inusannon fight over the planet Eingana, littering the planet with the debris of hundreds of starships. Refined element zero scattered by broken drive cores contaminates the environment, causing many native species to go extinct and those that survive to show a tendency to develop biotic powers.

Pre-Council Times (68,000 BCE - 500 BCE)
68,000 BCE

The Protheans achieve spaceflight and discover mass effect technology from the ruins of the extinct inusannon. They go on to establish a galaxy-wide civilization linked by the mass relay network with the Citadel as their capital.

At some point, the Protheans encounter a hostile race of machine intelligences that endanger their existence. To combat this threat, the Protheans aggressively assimilate many other spacefaring organic races into their empire. The Prothean Empire is able to fend off the machines in a conflict known as the "Metacon War".

48,000 BCE: Fall of the Protheans

The Prothean Empire collapses with the arrival of the Reapers through the Citadel. Although the Protheans had learned of the Reapers' existence from studying the ruins of previous civilizations and had begun to prepare, they were nonetheless caught off-guard. Over the next several centuries, the Protheans fight the Reapers system by system, world by world, and city by city. In the end, it is not enough. The Reapers methodically wipe out the remaining Protheans, as well as other contemporary races, and depart the galaxy to await the next cycle.

13,000 BCE

The turians of Palaven begin to develop civilization around this time.

6000 BCE

Seeking to escape the imminent explosion of their sun, an alien race constructs an AI-managed starship equipped with supercomputers containing a virtual world, into which some one billion of the aliens transfer their consciousnesses. The starship begins a journey throughout the galaxy which lasts for the next 8,000 years.

1900 BCE

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

A supernova propels the Mu Relay, the only point of access to the remote Pangaea Expanse, out of position. Concealed somewhere in the dense nebula formed by the supernova, the relay's position is effectively lost for centuries. Later, the rachni rediscover the relay.

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.

Council Era - Formation (500 BCE - 1 CE)
500 BCE: Founding of the Citadel Council

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 every member of the Union's inner cabinet; Special Tasks Group operatives then hunt down and eliminate the League.

300 BCE

The volus begin exploring and colonizing the stars shortly after discovering FTL.

First contact is made with the volus.

Eventually, the Citadel Council commissions the volus to draw up the Unified Banking Act, which establishes a standard galactic currency known as the credit and links all galactic economies. The turian Unification War occurs. The increasingly isolated and xenophobic colonies on the frontiers of turian space go to war with each other. After years of fighting, the Turian Hierarchy sweeps in and pacifies the remaining factions. Animosity between turian colonies continues for decades.

The Council grants the volus the honor of being the first non-Council species with an embassy at the Citadel, rather than a Council seat.

First contact is made with the batarians. They are granted an embassy a century later.

The asari discover the elcor home system and help the elcor locate and activate their nearest mass relay. "Within one elcor lifetime" they establish a regular trade route to the Citadel and are granted an embassy.

First contact is made with the hanar and the quarians. Both races are later granted embassies.

Council Era - War and Rebellion (1 CE - 900 CE)
1 CE: The Rachni Wars

The rachni,a species of highly intelligent hive-minded insects, are discovered when a Citadel expedition opens a dormant mass relay leading to their star systems. The rachni prove to be hostile and begin a war with the rest of the galaxy. Negotiation with the rachni queens is impossible because they cannot be contacted in their underground nests on the toxic rachni worlds.

80 CE

The Rachni Wars continue. The salarians make first contact with and uplift the primitive krogan, manipulating them into acting as soldiers for the Citadel Council. The krogan prove able to survive the harsh environments of the rachni worlds and pursue the rachni into their nests, systematically eradicating queens and eggs.

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

300 - 700 CE

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.

693 CE

Beelo Gurji, a salarian operative, is appointed the first Spectre by the Citadel Council.

700 CE: The Krogan Rebellions

Krogan warlords leverage veterans of the Rachni Wars to annex territory from other races in Citadel space. Eventually the Council demands withdrawal from the asari colony of Lusia, but the krogan refuse. A preemptive strike is made on krogan infrastructures by the Spectres. The Krogan Rebellions begin.

The Citadel Council makes first contact with the turians around this time and persuades them to aid in the war. After the kroganrespond to the initial turian offensive by devastating turian colonies with weapons of mass destruction, the turians vow to stop the krogan from ever becoming a threat again.

Sometime after the turians join the galactic community, the volus are accepted as a client race of the Turian Hierarchy.

710 CE

Realizing that the krogan will never give in as long as they can replenish their fighters, the turians unleash a salarian-engineered bio-weapon known as the genophage on the krogan. The krogan population starts its decline.

800 CE

The Krogan Rebellions end, though scattered krogan insurgent actions continue for decades. The turians fill the military and peacekeeping niche left by the decimated krogan.

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

Council Era - Expansion (900 CE - 2157 CE)
900 CE

The turians are granted a seat on the Citadel Council in recognition for their service in the Krogan Rebellions.

1400 CE

Extensive and unchecked industrial expansion on the drell homeworld Rakhana begins taking a significant toll on the planet's environment.

1600 CE

The first sightings of the Collectors are reported in the Terminus Systems. In Citadel space, the claims are dismissed as unsubstantiated rumors and tall tales.

1880 CE

Aria T'Loak arrives on Omega, a space station in the Terminus Systems regarded as the region's nominal capital. Aria is hired by the station's warlord as an enforcer and quickly becomes one of his most trusted lieutenants.

1895 CE: The Geth War

The geth, machines created by the quarians as a source of cheap labor, become self-aware. Fearing a geth uprising,the quarians begin dismantling them. The geth revolt against their quarian masters. In the resulting conflict--known to the geth as the Morning War--the geth systematically drive the quarians from their own worlds. The surviving quarians are reduced to living as spacefaring nomads aboard the Migrant Fleet. Contrary to expectations, the geth do not venture outside the former quarian systems into wider Citadel space, instead isolating themselves from the rest of the galaxy behind the Perseus Veil. As punishment for creating the geth, the Citadel Council closes the quarian embassy on the Citadel.

1921 CE

The geth begin construction of a mega-structure designed to house and simultaneously run every geth program in existence. Completion of the mega-structure, which would allow the geth to maximize their collective processing capacity, is the long-term goal of geth civilization.

1961 CE

April 12: Yuri Gagarin aboard the Vostok 1 becomes the first human to travel in space. Humanity becomes a spacefaring race.

2000 CE

The drell make first contact with the hanar around this time. With their homeworld Rakhana severely depleted and no spaceflight capability, the drell were poised for a massive population crash by 2025 CE. Agreeing to help, the hanar mount a large-scale rescue operation and evacuate approximately 375,000 drell to their own homeworld, Kahje, over the following decade. The remaining 11 billion drell on Rakhana gradually perish, warring over the last reserves of food and water.

2015 CE

SpaceX successfully lands and recovers the first stage of its Falcon 9 rocket after delivering 11 communications satellites to orbit.

This represents the first-ever orbital class rocket landing, and humanity’s first major shift towards sustainable space travel.

2103 CE

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

2125 CE

The yahg, an intelligent pre-spaceflight race, are discovered on the planet Parnack. Ambassadors representing the Citadel Council arrive on the planet and attempt to open diplomatic contact. After the ambassadors are killed by the predatory yahg, the Council ceases all contact with the yahg and declares Parnack off-limits.

Not long after the yahg are discovered, one yahg is captured for the Shadow Broker to study. With the Broker's assistance, the yahg rapidly ascends within the Broker's organization as "Operative Kechlu". Eventually, the Broker becomes wary of "Operative Kechlu" and attempts to have him terminated, but the order is sent too late. The yahg assumes the mantle of the Shadow Broker and directs the organization for the next sixty years.

2148 CE: Humanity Discovers Mass Effect Physics

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 Sol 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, which instantaneously transports them to another relay in Arcturus, 36 light-years away. The explorers discover that the mass relays are part of a vast network, making travel across the galaxy possible.

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

2150 CE

The Systems Alliance begins the first surveys for colonization prospects outside the Sol System. One of these surveys discovers the planet Terra Nova.

2151 CE

To defend its expanding territory, humanity begins constructing a massive military fleet and space station at Arcturus, the nexus of several key mass relays, even though they have yet to encounter another intelligent spacefaring race.

An accident at Singapore International Spaceport exposes hundreds of humans to dust-form element zero.

Roughly 30% of the children born in Singapore after element zero exposure suffer from cancerous growths. After his mother is exposed during the accident, Kaidan Alenko is born later that year with biotic potential.

2152 CE

The Delta Pavonis Foundation, a major consortium based on Earth, begins settlement of humanity's first extra-solar colony world, the planet Demeter. Later that year, additional colonies are founded on Eden Prime and Terra Nova.

2154 CE

April 11: Shepard is born.

There is a second publicized accident involving the exposure of humans to element zero.

Council Era - Advent of Humanity (2157 CE - 2183 CE)
2157 CE: The First Contact War

Humanity makes violent first contact with another spacefaring race: the turians.

The turians observe human explorers attempting to activate a dormant mass relay, a practice forbidden by galactic law after the Rachni Wars, and attack. Over the next three months, a brief but tense conflict known by humans as the First Contact War and by turians as the Relay 314 Incident ensues.

The First Contact War culminates in the turian siege and occupation of Shanxi, the first human world to fall to an alien race. Admiral Kastanie Drescher leads the Second Fleet in battle against Shanxi's occupiers one month later, catching the turians by surprise and evicting them from the planet.

The turians prepare for a full-scale 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.

An anonymous extranet manifesto is published following the end of the First Contact War. The manifesto calls for an army, a "Cerberus", to be established to defend humanity against inevitable alien attacks. Derided as "survivalist rhetoric written by an illusive man", the manifesto is quickly forgotten by the media.

2158 CE

Humans learn the potential of biotics.

An international effort to track element zero exposures begins. Roughly 10% of recorded exposed children show indications of biotic ability.

2159 CE

Saren Arterius becomes the youngest turian to be inducted into the Spectres.

The Systems Alliance purchases Gagarin Station for a fraction of its construction cost, and converts the facility into a biotic research and training facility.

2160 CE

The Systems Alliance Parliament is formed.

With the existence of human biotics firmly established, the Biotic Acclimation and Temperance Training (BAaT) program is set up on Gagarin Station to train potential candidates and develop biotic implants.

The biotic drug red sand is first used.

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.

The first experimental L1 biotic implants are used in humans.

A series of starship drive failures are orchestrated over populated areas on human colony worlds, causing widespread exposures to element zero. This results in a second generation of humans born with biotic potential.

The Leviathan of Dis, a genetically-engineered living starship believed to be nearly a billion years old, is discovered by a batarian survey team on the planet Jartar. The Leviathan disappears under dubious circumstances after a batarian dreadnought passes through the Dis system.

2164 CE

Ivor Johnstagg is sentenced to 21 years in prison for attempting to assassinate Venta Tox, the volus ambassador to the Citadel. Although Johnstagg claims to be acting on behalf of the radical human political party Eternal Earth, no connection is found and Johnstagg is diagnosed with paranoid schizophrenia. Backlash from the assassination attempt jeopardizes the Systems Alliance's bid for an embassy on the Citadel.

2165 CE

Humanity continues to expand, founding more colonies and establishing trade alliances with many of the other species whorecognize the authority of the Citadel Council. In 2165 CE, 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.

Terrorists steal antimatter from the Alliance cruiser SSV Geneva. The sole figure arrested names his sponsor "Cerberus". This is the first such incident of sabotage connected to the Cerberus organization.

2167 CE

The magazine Fornax is launched.

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.

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

Industries.

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

The first A-61 Mantis Gunships are produced.

2171 CE

In protest at the refusal of the Citadel Council to limit human expansion in the Skyllian Verge, the batarians close their embassy, withdraw into their home systems, and effectively become a rogue state.

Cerberus assassinates Pope Clement XVI on Earth via rosary beads coated with toxic substances; his death is attributed

to age and heart failure. His successor, Pope Leo XIV, espouses beliefs more in-line with Cerberus' ideals.

2172 CE

On Gagarin Station, "Eliza" becomes the first sapient AI created in the Systems Alliance.

2173 CE

A fly-by over the world of Armeni discovers odd surface protrusions. Upon closer inspection, they are identified as elaborate crypts made by the zeioph, an extinct spacefaring race. Various human universities seek to perform excavation, but Council laws that hold burial sites as sacrosanct prevent this. An ongoing debate over the issue ensues.

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, is assassinated by Cerberus operatives while en route to Shanxi. Publicly, Menneau's disappearance is never explained.

2175 CE

On a survey mission to 2175 Aeia, an important colonization prospect for the Systems Alliance, the MSV Hugo Gernsback disappears and is presumed destroyed.

Cerberus covertly contacts Michael Moser Lang, a political dissident on Earth, and provides him with funding to purchase weapons. Cerberus continues

to monitor him after contact ends. One year later, Lang assassinates United North American States president Enrique Aguilar and Chinese People's Federation premier Ying Xiong. The resulting political shuffle benefits Cerberus' shell companies and plans for the Systems Alliance Parliament. 2176 CE

Batarian-funded pirates and criminals launch a surprise attack, later known as the Skyllian Blitz, on the human colony of Elysium. 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.

The Anhur Rebellions, a civil war waged over the practice of slavery, begin on the human and batarian colony world of Anhur and spread throughout the Amun system. Abolitionism supporters hire the Eclipse mercenary group to fight the batarian pro-slavery Na'hesit faction.

Miners at the T-GES Mineral Works facility on Mahavid uncover a Leviathan artifact. The miners are enthralled by the Leviathans for the next ten years and are used to carry out numerous experiments.

The Andromeda Initiative, a privately-funded multi-species endeavor created to explore and colonize the Andromeda Galaxy, is founded.

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

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.

The Alliance tracks several pirate FTL exit vectors over a period of six months using covert monitoring devices planted on Theshaca's moons, leading the Alliance Navy to eight major pirate anchorages. Since the "Theshaca Raids", no ships from the Terminus Systems have entered the Hong system.

A lethal airborne virus sweeps through the quarian Migrant Fleet.

2182 CE

Admiral Kahoku of the Systems Alliance begins investigating suspected Cerberus activities.

2183 CE

Humans and turians collaborate on an engineering project co-sponsored by the Citadel Council: an experimental frigate with a prototype stealth system, the SSV Normandy. David Anderson is given command of the ship, and Commander Shepard is assigned as executive officer.

Recent History
A short timeline for relevant information leading up to the creation of the RIFT.

2183 CE

The human colony of Eden Prime is attacked by the geth, initiating a wider conflict between humans and geth known as the Eden Prime War. After exposing the involvement of rogue Spectre Saren Arterius in the attack, Saren is perused in his search for the Conduit, and his plans were discovered later revealed to be part of a larger plot orchestrated by the Reaper Sovereign to return its kind to the galaxy. Sovereign and a geth fleet assault the Citadel station, killing hundreds in the process. Saren is defeated, and the Alliance Navy destroys Sovereign, preventing the release of the Reapers. The Citadel Council was saved from certain death when human ships were sacrificed, allowing the Councils own ship to make their escape. Because of this, humanity has been painted in a brighter light in the eyes of the council species and was granted a seat, though not everyone is happy with their rise to power. One month after the Battle of the Citadel, the SSV Normandy is attacked and destroyed by an unidentified assailant, resulting in the death of Commander Shepard. Later, the Systems Alliance officially declares the first human spectre, Shepard, "killed in action".

2184 CE

The Eden Prime War comes to a close. Although most geth forces in Citadel space were destroyed in the Battle of the Citadel, holdouts yet remain. The Alliance Navy reduces its patrols, relying instead on civilian ships to report any geth activity. Raids are carried out against identified geth outposts, but the conflict is essentially over.

2185 CE

The events of Mass Effect 2 continue. Commander Shepard is revived and tasked by the Illusive Man to investigate the mysterious disappearances of entire human colonies in the Terminus Systems. Investigation of the attacked colony of Freedom's Progress reveals the enigmatic Collectors from beyond the Omega 4 Relay to be responsible for the disappearances. After assembling a capable team, Commander Shepard uses a captured Reaper IFF to safely traverse the relay and infiltrate the Collector base. Shepard succeeds in eliminating the Collector threat, destroying the base and saving humanity throughout the galaxy from certain destruction, though there is still the threat of the Reapers at hand. A large faction of "geth heretics" are destroyed when their space station exploded due to the actions of the human spectre. Liara T'Soni locates the Shadow Broker's concealed base on the planet Hagalaz. The Shadow Broker, exposed as a yahg, is killed. Liara takes control of the Broker's organization, intending to use the Broker's vast information network to aid Shepard's fight against the Reapers.

2186 CE

January 23: SSV Budapest, an Alliance cruiser that sparked a diplomatic crisis between the Earth Systems Alliance and the Batarian Hegemony, withdraws from the Bahak system. The Bahak system is subsequently destroyed following the explosion of its mass relay when an asteroid was sent into the relay in order to delay the Reapers' invasion. Hundreds of thousands of batarians living on Aratoht are obliterated in the blast.

 September 21 

The REAPER WAR begins.

Several months after the destruction of the Alpha Relay, the Reapers invade the galaxy through batarian space and attack Earth. A Prothean superweapon design is discovered on Mars that could end the Reapers' threat once and for all. To build the Crucible and take back Earth, the various races of the Milky Way galaxy must unite and embark on a journey to save all life as they know it as galaxy-wide war rages. In the quest to destroy the reapers, Commander Shepard cured the genophage much to the delight of krogans throughout the galaxy. Lead by Urdnot Wreav and Urdnot Bakara, the krogan became a formidable force against the reapers. In the Perseus Veil, tensions between the quarians and the geth finally come to a close, as geth are upgraded to a true intelligence, and begin to assist the quarians and the rest of the galaxy against the reapers.

November 2

When the crucible project failed and the fleets over earth were decimated, the crucible now sits dormant on the citadel station swarming with reapers. To the galaxy, it seemed that all hope was lost -- however, that is never the case. One week after the massacre above earth, the Council put forward a plan, Operation: Event Horizon.

November 24

RIFT's strike force is finally assembled with hand-picked candidates coming from all across the galaxy, as well as a few others. It is then revealed to them that the mission brief for Operation: Event Horizon presented to the public was no more than a front for a much deeper and complicated mission. You see, the council knew all about the catalyst, or at least, they knew that it was a dead end. With their last means of survival now destroyed, the Council chose to withhold this information to keep the hope of the galaxy alive, and to keep the reapers distracted as the galaxy threw all it had left at them.

The true purpose of Operation: Event Horizon? To discover an uncharted world suitable for life. The Council's true plan is to build a bunker, massive in scale, and capable of holding the rest of the Galaxy's survivors as the reapers complete their harvest. However, with reaper forces now having access to the Citadel's starcharts, the mission became much more complicated. This is where RIFT came in. With one of the galaxy's most advanced warship at their disposal, they are tasked with finding this "golden world". While the mission may seem impossible at first, the team has now discovered a lead. As thousands die by the minute, it is up to RIFT to find some way to complete their mission, or die alongside the rest.

December

The reapers continue to wreak havoc on the galaxy. Some call it the apocalypse.

40% of the Milky Way's population have either been killed, or are missing in action. The death toll continues to rise.