From Halopedia, the Halo wiki
- Over 500,000,000 years ago, the Precursors were stated by the Gravemind to have created the Domain, coalescing the sum of their knowledge—encompassing a hundred billion years—into a unified reservoir integrated into their many neural physics artifacts in the Milky Way galaxy. However, the Domain may have been first created long before this, as Forthencho, acting as a messenger for the Gravemind, later stated that it had existed for many billions of years.
- Halo: Silentium, pages 208-209
- Halo: Silentium, page 322