40,000 BCE

The year 40,000 BCE is a year in the distant past.

Unknown

 * Circa 40,000 BCE, an unidentified alien vessel crash-landed in Sector 1215 of Installation 04. Sometime prior to the crash, the ship started broadcasting a distress signal repeating every 72.83 seconds. After attempting to translate it, 343 Guilty Spark blocked the signal, as no communication revealing the location of any of the Halos was allowed.