97,495 BCE

Unknown
It is implied in the description and beginning of Halo: Silentium that the novel begins several years after the end of Halo: Primordium. On page 193, while testifying to the Master Juridical, Master Builder Faber states that he and his forces held a salient against the Flood for three years after Mendicant Bias' attack on the Capital. Since the Master Juridical would know how long Faber had been missing since the fall of the Capital, it would be futile for the latter to claim that he had been running his private operation for more than the time he had been confirmed to be missing. As such, his statement about holding off for three years can be considered the minimum figure for the duration of his exile. However, it should be noted that Faber may have remained missing for more than that time, as the three years of holding that particular salient may have constituted only a portion of the operations he undertook during his exile. Faber's testimony took place after his return to the ecumene, which coincided with his rescue of the Ur-Didact. As stated on page 28 of Silentium, the Ur-Didact's return had already occurred some time prior to the evacuation of Erde-Tyrene and the Librarian's deposition by Catalog. There is a four-year period between the Librarian's and the IsoDidact's parting during the evacuation of Erde-Tyrene and their reunion on Nomdagro (Silentium, page 197). Although it is not definitely stated how much time passes between the meeting on Nomdagro and the firing of the Halo Array, the almost continuous recounting of the events past Nomdagro up until the Halos' activation in Silentium would suggest no more than several days or weeks passed in the interim. However, this does not take into account the possibility of increased time dilation effects due to the Precursor-empowered Flood's corruption of spacetime, which interfered with the Forerunners' slipspace travel in the final years of the war. The year 97,495 BCE for Installation 07's disappearance is calculated on the basis that seven years passed between the events of Halo: Cryptum and the firing of the Halos, therefore indicating that the events described on this page took place fifty years before the firing of the Array. Due to several ambiguities it is possible that the events took place several (though likely no more than five) years earlier than this, but anything beyond the known minimum figure remains in the realm of speculation. It should be noted that the Halo Encyclopedia lists Mendicant Bias' conversation with the Gravemind as having begun on 100,043 BCE, or 43 years before the approximate date for the firing of the Halos. However, because the Encyclopedia itself notes that the timeline is only approximate and due to the manifold revisions to Forerunner-era canon introduced by The Forerunner Saga, the information from the novels can be considered to be of superior canonicity to the more unreliable and rough dating provided in the Encyclopedia. the Forerunner Ecumene Council assigns the Contender-class ancilla Mendicant Bias to test Installation 07 near Charum Hakkor. The installation, fired on a system-wide power setting, destroys all neurologically complex life and Precursor structures in the system and accidentally liberates an ancient Gravemind known as the Primordial, which is transported on the ring on Master Builder Faber's orders. Soon after, Faber tasks Mendicant Bias with interrogating the Primordial and Installation 07 is transported in an unknown location. Over the course of their 43-year conversation, the Primordial manages to turn Mendicant Bias against its makers and causing it to join the Flood's cause to destroy the Forerunners.
 * In approximately 97,495 BCE or slightly earlier, The Halo Array was fired in 97,445 BCE. Mendicant Bias' test-firing of Installation 07 and the Halo's subsequent disappearance took place 43 years before the installation's return during the events of Halo: Cryptum (Halo: Cryptum page 244 and Halo: Primordium page 192). Halo: Cryptum takes place a minimum of seven years before the firing of the Halo Array, which can be extrapolated from a number of statements in Halo: Silentium:
 * The Librarian returns to Earth to index the human species. Sample members of the species are removed from the planet and held on the Ark.