Age of Abandonment (Earth-2042)

The Age of Abandonment, also called the First Age of Abandonment, was the name given to the first period of Covenant history, even though it technically predated the formation of the Covenant. This age refers to the time from 2200 BBY, which marked the start of the Stoic-Reformist conflict, and 2100 BBY, when the Forerunner Dreadnought left Janjur Qom. In the ceremonial Progression of the Ages, this age is represented by an obsidian stone.

During the ritual, the appropriate dialogue is as followed:

Leader: "Abandonment."

Congregation: "The First Age! Ignorance and fear!"

Source

 * https://www.halopedia.org/Age_of_Abandonment