The Mirucians:

Before their enslavement by the kthid, the mirucains lived only in the narrow band of warm, savanna spanning the equatorial region of their temperate home planet. Dwelling in small, tightly knit clans, they subsisted as semi-nomadic carnivorous hunter-gatherers, preying on the large herds of herbivorous animals that they shared their habitat with. By comparison to most sapient species of the noctis sector, mirucains display a rather extreme degree of sexual dimorphism. Females are muscular and toughly built, standing at 180-200 cm tall with a pair of large, curved horns that are used for both hunting and combat. Mirucain males meanwhile were much shorter and lighter, usually around 150cm with slender, lithe builds. They were born much more rarely too, with only around 1 in 6 miruacin births resulting in male offspring.
With the rarer males considered a delicate and precious resource, they were kept protected within the hidden tunnels of the clan warren, while the females hunted prey above ground. Each clan was led by a matriarch, who claimed and defended her position through contests of strength, resulting in only the most powerful female claiming such a title. Lacking the technology to smelt even simple metal weapons, the mirucains relied on their powerful kicks and blows from their horns to bring down larger herbivores. On the hunt, groups of females would pick out weaker members of the herd and run them to exhaustion before the matriarch would lead her clan to surround and strike down the animal from multiple directions before it could be finished off.
Living a difficult and often harsh existence, competition between the scattered mirucain clans for both prey to hunt and males to breed with was fierce. Each group staked out a territory around which they roamed and hunted, and any trespassing from rival clans was met with violent reprisals. Raids conducted between clans resulted in the claiming and kidnap of any males the invaders could snatch. The constant skirmishing led to the mirucain clans tending towards the insular and aggressive, with strange females treated invariably as enemies. There was scope for more friendly relations between clans, who could exchange males at peaceful meeting grounds, but these were relatively rare events.
The sheer degree of difference between mirucain and females hints at more curious origins of their species. Genetic analyses reveal that the smaller male physiology derives from a smaller, very closely related species that no longer seems to exist beyond that. It can be theorised that at some point their distant evolutionary past, the mirucain females overwhelmed and slaughtered their weaker kin, taking all their males as prizes. The rampant interbreeding that followed led to the two species combining, with the result being much weaker and more submissive males paired with larger, aggressive females. In any case, no matter their uniqueness, with the prized males pitilessly slaughtered during the kthid invasion of their warrens, and the surviving females dragged into slavery by their brutal new masters, the mirucains themselves seem now doomed to extinction.
Stereotypes: With a tendency to lash out against those they consider strangers, mirucains have a not undeserved reputation for being violent and combative towards other species. The relatively primitive stage of development they had reached at the time of their enslavement and their resulting terror of the advanced technology that was used to tear them from their homeworld has led many kthid to consider them stupid, weak or cowardly.