Simplified Warframe timeline

pre- Orokin Era

• Very little is known of this time period
• The year 1999 is known to be a pivotal one, with an outbreak of the Technocyte plague
• The Radiation Wars may also have taken place prior to Orokin rise

Orokin Era / Void Era

• The Orokin become the dominant human civilisation
• The Orokin create cephalons, Dax soldiers, and Grineer clones
• The Orokin discover the Void and incorporate it into their technology
• The Orokin build the Solar Rail network to connect the Origin System
• Parvos Granum founds the Corpus as an element of Orokin society
• The Orokin build the Zariman 10-0 ship to colonise the Tau System; the ship is lost to the Void
• The Orokin create the Sentients to build a Solar Rail to Tau and terraform its planets; this is mostly successful

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The Old War

• The Sentients rebel against the Orokin, triggering a war that lasts hundreds of years
• Sentient adaptation and hacking make most advanced technology ineffective
• The Orokin respond with biological warfare: Infested monsters, Grineer clones, and "warframe" bio-drones; all only partially effective
• The Zariman 10-0 returns from the Void, with no adult survivors. The orphaned children have been traumatised and infused with the energy of the Void. The Orokin discover that the children can control the warframe bio-drones, and turn them into child soldiers.
• The Zariman children ("Tenno") and their warframes win the Old War, defeating the Sentients
• When the Orokin gather to celebrate their victory, the Tenno turn on them and slaughter them all

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The Collapse

• The surviving Orokin are hunted down by the Tenno and killed (with few exceptions)
• Orokin technology no longer works due to gene-locks
• Lua is phased into the Void to keep it safe
• Infestation breaks out all across the System, causing chaos and death
• The Grineer, led by an unusually intelligent mutant specimen, become a growing threat. The Twin Sisters fight against them but eventually earn their respect, and become their queens.
• A rogue Sentient arrives on Earth and demolishes all the Orokin Towers except the Tower of the Unum, where it is defeated by the warframe Gara
• The Tenno enter cryosleep

The Interregnum

• In the wake of the Collapse, humanity settles into a dark age lasting at least a millennium
• Warring factions struggle over lost technology while scattered colonies try simply to survive
• At some point, the space-faring Ostrons establish a home base near the Tower of the Unum, named Cetus

Modern Era / Tenno Era

• The Twin Queens order Captain Vor to find and destroy Tenno cryopods; this prompts the Lotus to begin the awakening of the Tenno
• The Infestation, long contained, is released by Grineer scientists, leading to recurring outbreaks
• Deimos, hidden in the Void, returns to real-space, bearing the Entrati family and their Orokin secrets
• The Grineer-Corpus war breaks out and continues for most of this time period
• Alad V leaves the Corpus, attempts to use the Infested to take over the System, fails, and eventually asks the Tenno for help in obtaining a cure for his own progressive Infestation
• Tyl Regor unearths the tomb of Hunhow, Sentient leader from the Old War. Hunhow awakens and attempts to exterminate the Tenno. Although he is unsuccessful, his actions result in Lua returning to real-space, as well as the Tenno learning the truth of their origins.
• The Elder Queen of the Grineer attempts to use Continuity on the Chosen Operator, but fails and dies

The New War

• Orokin Executor Ballas emerges from hiding and abducts the Lotus, triggering her Sentient programming
• Ballas gains control of Sentient remnants in the outer Origin System through deception and scheming
• Ballas launches a Sentient invasion of the Origin System, defeating the combined Grineer and Corpus in a decisive victory in the Veil Proxima
• Ballas confronts the Chosen Operator and imprisons them within their own past, rendering all Tenno in the System powerless
• Ballas conquers the Origin System and establishes the empire and cult of Narmer, with himself as its messiah-king; he rules for an undefined period of months or years
• The Drifter, an alternate version of the Chosen Operator, paradoxically arrives in the Origin System and helps the Operator escape the past
• The Operator and the Drifter are united into a single individual and they confront Ballas
• Ballas, in desperation and rage, opens a portal to Tau, piercing a hole in the fabric of reality. The Chosen Operator defeats Ballas, and the Lotus kills him and closes the portal.

post- New War

• Narmer remnants continue to be active, led by Pazuul; the Tenno and Kahl-175 fight to keep them suppressed
• The Zariman 10-0 appears in the Origin System again; the Tenno meet the Holdfasts and fight to protect the ship
• Ballas' portal greatly empowers the Indifference, and the Murmur attacks Albrecht Entrati's secret labs below Deimos
• The Kalymos Sequence is activated, summoning the Tenno to the labs to fight the Murmur and awaken Albrecht's assistant Loid