The homeworld of the Kig-Yar is the satellite Eayn (orbiting Chu'ot) which is very similar to Earth in atmosphere and temperatures. On this planet, the Kig-Yar were able to evolve in sentient creatures. Their species was relatively secluded from each other due to their strong pack mentality. Each pack, or clan, sailed Eayn's seas as pirates, raiding the encampments and settlements of rival clans.
This way of living separated the species from each other, but this clan-mentality would eventually be overcome and unite the species once more. But due to the harsh environments on Eayn, an evolutionary split had happened, creating three distinct sub-species of Kig-Yar: The Ruutian, the T'vaoan and the Ibie'shan; the T'vaoan were nearly wiped out after the events on Reach.
Each Kig-Yar sub-species had their own abilities and distinct look, but all were very fierce fighters, using their arm-held energy shields and impressive quickness. Kig-Yar are also known for their large array of weaponry, depending on their rank. But Kig-Yar ground-troops are most commonly seen with either a Plasma Pistol or Needler.
Now together, the Kig-Yar were able to produce technology which would put them in Technology Tier 4, which means they were able to colonise neighbouring planetary bodies. Going back to their clan mentality, several smaller groups of Kig-Yar settled on the asteroids orbiting Chu'ot.
Absorbed in the Covenant
For many years, the Kig-Yar existed of a large population on Eayn and several smaller populations on the nearby asteroids. But then, suddenly an alien ship arrived in their system. Not knowing what to make of it, the Kig-Yar readied their military and decided to attack the vessel. But instead of fighting, the ship disappeared once again, only to return later as part of a much larger fleet. As the Kig-Yar on Eayn were overwhelmed by this assault, the Kig-Yar on the asteroids were able to sneak behind the overwhelming forces and launch a mildly successful counter-attack. But it was no use, the invading aliens were much too powerful.
Not wanting their race to be wiped from existence, the Kig-Yar grudgingly accepted the Letters of Marque, and were now official members of the Covenant Empire. Though often this was merely used as an excuse to continue their plundering lifestyle. The Kig-Yar would spend much of their time preying on the ships of the Covenant's enemies, such as humanity. As one of the less physically imposing fighting species in the Covenant, the Kig-Yar are ranked low; around the same level as the Unggoy. This caused a lot of friction between the two species, with both species trying to harm the other.
There are many examples of this friction, but the most notable one happened in the year 2462, when after Unggoy encroaching on the Kig-Yar's habitats and displacing their nests, the Kig-Yar took revenge. Some Kig-Yar in High Charity attempted to poison Infusions, recreational narcotics the Unggoy enjoyed, which would have left the Unggoy sterile. Although a junior staffer in the Ministry of Concert found evidence of this, the High Council failed to properly investigate the incident, culminating in the Unggoy Rebellion.
The Kig-Yar led Missionary ship Minor Transgression was scanning the edges of Covenant-held space for Forerunner relics when it stumbled upon some alien ships. After having boarded and subsequently destroyed the first one, they entered a second ship encountered their very first human. This event turned out to be huge on the fate of the galaxy, as this would eventually lead to the Human-Covenant war.
But while the Covenant was busy fighting the humans, they were unable to locate either their homeworld or any major settlements. By orders of the Prophet of Truth, some Kig-Yar merchants allied themselves with humans. Some Insurrectionists and survivors from the UEG colony world Madrigal had founded a small settlement on an asteroid in the 23 Librae system. They were discovered by these Kig-Yar, and were helped to eventually create The Rubble. At its peak, it consisted of hundreds of hollowed-out asteroids, moved together and connected by docking tubes.
This settlement was then used by the Kig-Yar to trade weaponry with the Insurrectionists in return for information. The weapons they were handed were modified and sent to other Insurrectionists across the galaxy. When the Prophet of Regret found some of the weapons on sale on High Charity, not knowing that they were part of the Prophet of Truth's plan, he sent some of the Covenant's top soldiers to silence the "rebels"; while the UNSC sent the Light Frigate UNSC Midsummer Night to investigate Insurrectionist activity. With both sides of the Human-Covenant war approaching the Rubble, a larger conflict was inevitable, resulting in the Battle of the Rubble. The exact number of casualties was never specified, but it is known that Supreme Commander Thel 'Vadamee took part of the engagement.
After the Great Schism had divided the Kig-Yars once more, some Kig-Yar took up their old ways of pirating, this time interplanetary piracy, others remained peaceful with the humans, while others still sided with the Covenant remnants factions and actively fought the humans.