Covenant

The Covenant Empire, or Covenant, was an Interstellar theocratic hegemony in the Halo Universe. It was made up of multiple alien species that maintained control over a large portion of the Orion Arm in the Milky Way galaxy. The Covenant was a political, military, and religious affiliation, originally a mutual alliance between the San'Shyuum and Sangheili following a brutal conflict between the two warring races. Its expansion to include at least six other races united in the worship of the Forerunners and the Halo Array soon began after the original formation.

After their first contact with the UNSC, the Prophets learned that the humans were actually reclaimers. This revelation would have falsified the covenant religion so the prophets covered the truth and declared a holy war against the human race.