Covenant history
The Age of Discovery is a time period in Covenant history. This Age took place during the Elite-Prophet war. It is believed that during this Age, the Prophets (possibly with the help of the Engineers) discovered the remains of Forerunner technology, probably giving birth to the Covenant religion with its central theme that the activation of the Halos would begin the Great Journey for the Covenant, leading them to salvation.
This "Great Journey" would lead to the total destruction of anything within three radi of the galactic centre. It is unfortunate for the Covenant and all it's members that they are being led on a path to death by Prophets who did not understand the secrets or potential of Halo.