The Luminoth are a technologically advanced race of moth-like beings who have an intense spiritual fixation with light, and are quite similar in technology to the Chozo, due to having been in contact with them before the latter's sudden extinction or transcendence. They are the last of the known Higher races, as both the Chozo and Alimbics are now likely extinct, the former assumed to have nothing more than an ethereal state of being in the universe, the latter being wiped out by Gorea with horrifying speed and are nothing more than telepathic essences now.
The Luminoth's earliest history states that they were "born among the stars." If they had an original homeworld, it has long been lost, and the Luminoth existed as interstellar nomads for many generations. Eventually, influenced by other advanced races (including the Chozo) they decided to choose a homeworld for themselves, settling on the planet Aether. They lived in peace on their chosen homeworld until a mysterious meteorite carrying extremely high amounts of Phazon crashed into the planet. Dark Samus arrived much later to the planet, most likely because it had a need to feed on the Phazon which impacted the planet much earlier. The explosive impact of the meteorite literally tore the planet in two, creating a second Aether, known as Dark Aether. On that planet, the Ing thrived. It seems that all of the Phazon from the impacted meteorite transferred only to the dark version of Aether, as it doesn't seem to appear in Light Aether. When the Ing discovered portals that took them to Aether, they began invading Luminoth territory by possessing several creatures (including Luminoth soldiers and technology themselves). After a near seventy-year-long bitter war of attrition, they had defeated the Luminoth, who retreated into the Great Temple and for the most part went into cryogenic stasis to await a savior.