History of the Covenant

The Covenant, like almost all cultures, keeps a record of their history using their own methods of timekeeping. Unfortunately, the exact measures, if any, of these are a mystery, and there are hints that there may be multiple divisions of each age (9th Age of Reclamation, for example.) What is known is that the Covenant divide their recorded time into seven Ages, divided based on notable events within each. Each age is not necessarily a period of time, but a description of the events within it.

It is speculated that the Age of Reclamation will be the last of the ages, when the Covenant will fracture during their Civil War.

Age of Abandonment
The Covenant traces its history back at least 100,000 years, when an ancient species (not yet confirmed as aliens) called the Forerunner activated the Halo installations, disappearing from the galaxy. This is referred to as the Age of Abandonment by the Covenant.

Age of Conflict
At some point before the Covenant’s formation, it's been recorded that the Sangheili and San 'Shyuum waged war against each other, apparently in a power struggle, in what is called the Age of Conflict.

Ages of Discovery & Reconciliation
What is known is that the Prophets' discovery of ancient Forerunner artifacts during the Age of Discovery and the end of the war during the Age of Reconciliation, became the foundation on which the Covenant was founded upon. The Prophets promised to find the means of the Forerunners' transcendence and the Elites promised to protect the hierarchy. These ages marked the beginnings of the Covenant, the start of the Covenant’s search for Forerunner artifacts and presumably the Covenant Writ of Union.

The Covenant ship Truth and Reconciliation that appeared on Alpha Halo may have been named after this time period.

Age of Conversion
These were followed by the Age of Conversion, where the Covenant started their subjugation of other species in their search for Forerunner artifacts, incorporating them into their society, adding their strengths to their own. It is likely that the Taming of the Hunters occurred during this time period, requiring the creation of another Arbiter and defeated them only by threatening to destroy the homeworld of the Hunters. This period most likely included the incorporation of the Unggoy, Kig-Yar, Yanme’e and Huragok in separate Ages of Conversion.

Age of Doubt
The Age of Doubt is speculated to be a group of periods during which many of the Covenant began to lose faith in their mission. During the 29th Age of Doubt, the Grunt Rebellion occured, instigated by the Jackals, requiring the creation of an Arbiter to quell. The last Age of Doubt, the 29th, ended in the year 2525, in human counting, leading into the Age of Reclamation.

Age of Reclamation
The Age of Reclamation was marked by the Human-Covenant War and the incorporation of the Jiralhanae. The reasons for the war are currently unknown, though the subjugation of the Brutes led in turn to another major event – the Civil War of the Covenant, otherwise known as the Great Schism, with the expulsion of the Sangheili from the Covenant or the "Changing of the Guards" and their (at least grudging ) alliance with the Humans.

It also marks the discovery of several Forerunner installations, such as the Sacred Rings and the Ark.

The name may originate from the belief that Humans are Reclaimers.

Trivia

 * The Covenant does not base their time on one age coming after another, they base the age on the state and being of the Covenant, entirely. For instance, the 9th age of doubt did not come before the 9th age of Reclamation. It is instead the 29th age of Doubt and then the 9th age of Reclamation.