The origins of the Halo universe can be traced back to an ancient race of super advanced beings known as the Precursors. This is their story — and the beginning of the story of the Forerunners.
With a universe as jam-packed full of complex lore as Halo’s, it’s hard to believe that there was a time when the Milky Way galaxy was barren. However, that is exactly the case. There was a period in which nothing lived; the entirety of the galaxy was devoid of life. It was not until the arrival of the Precursors that the Milky Way became a home for biological life forms.