The Halo universe can be broken up into several distinct eras.
AboutThe history of the Halo universe spans hundreds of millennia, from the time of the Forerunners one-hundred thousand years ago, through the formation and growth of the Covenant, to humanity’s struggle amidst the stars. These are the key time periods in the Halo universe, and their importance to the greater lore.
Forerunner EraThe Forerunners dominated the Milky Way for the better part of fifteen-million years.
Human-Covenant WarHumanity hoped that first contact would be a peaceful and mutually beneficial interaction. It was not.