"I pledge my blade to a fallen cause, fraught with foes and dangerous claws. I pledge my heart to a righteous group, where I'll become a gracious troop. I pledge my soul to the Followers of the Forgotten Oath."
―Initiation ritual of the Followers of the Forgotten.
The Followers of the Forgotten were a group of fanatical Sangheili that split off from the baseline Covenant religion to form their own cult centered around a similar set of beliefs. While they share the majority of the beliefs with the main religion, one major difference is that the Followers do not believe in the Great Journey, believing that ascending to godhood would defeat the whole purpose of Forerunners being gods and therefore deemed it heretical. At their peak the Forgotten had close to several million followers, but this large following collapsed during the Great Schism. A great factor in this was due to dissent from within, when the cult's enforcement leader Grono 'Yendam murdered the High Priest Qav 'Bagozee, thus rendering the group without leadership.
With the once powerful cult now fragmented, Grono created a splinter sect made up of various pirates, marauding as the only remaining active worshippers. Eventually, even this remnant was destroyed in 2556, and it seemed that the Followers of the Forgotten had come to an end. However, fours years later, the same Sangheili Grono enacted the Remembrance call, summoning thousands of former members from across the galaxy to unite once more in their faith of the Forgotten Oath. With a large following, and a small fleet to match, 'Yendam declared himself the leader of enforcement and religious matters, both the High Priest and Supreme Warden. With an Oracle known as 589 Curious Puzzle confirming the falseness of the Great Journey, they would eventually venture to a refuge outside of the galaxy to enlist the help of a Forerunner Builder titled the Carpenter, who had created Puzzle.