Intergalactic space

"That's...our galaxy. We're beyond the rim."

- John-117 on Installation 00

Intergalactic space is the region of space between galaxies. The volume of intergalactic space is mostly empty and has an extremely low density. In rare cases, naturally occurring objects such as stars may be found outside galaxies. The astronomical objects closest to the Milky Way Galaxy are the Magellanic Clouds, two small satellite galaxies where the Flood were said to have first arrived to the galaxy around 110,000 BCE.

The Forerunners were capable of effortlessly traveling into intergalactic space, and even constructed at least two major installations, known as Arks, there. One of these structures, Installation 00 or the lesser Ark, became the site of the final battle of the Human-Covenant War in December 2552. For purposes other than the usage of the Arks, the Forerunners rarely ventured into intergalactic space, as there were no resources of interest. After the Didact was revived from his Cryptum circa 100,000 BCE, his ship made a series of irregular slipspace jumps to prevent core authority from tracking the journey; one of these jumps led into intergalactic space.