Forerunners

&nbsp The Forerunners were an ancient race existing approximately 100,000 years before this current age. the forerunner race were highly intelligent beings, able to create worlds and sentience. this technology proved vital in their war with the Flood, where they ultimately sacrificed themselves and all other life to prevent the Flood from consuming the biomass from this galaxy and move on to others.

They did this using the Halo arrays, installations set about the galaxy that, when fired, obliterated all life.