Zarr

 Zarr is a humid jungle planet in the Rawrca system. Though very hospitable to life and rich in desirable minerals, it is also the home of the violent lirrax, and as such is considered too dangerous for colonization by other species.

Description
The only planet within the habitable zone of the Rawrca system, Zarr offers a diverse range of ecosystems ranging from lush rainforests to arid deserts, and thus supports millions of different life-forms. Of those, at least three species are known to be sentient - the lirrax, the taaria, and the ahm. There has historically been very little contact between these species, as the taaria seldom leave the deserts, and the massive, beetle-like ahm make their homes in caverns beneath the ocean.

The Protheans built settlements on Zarr over 50,000 years ago, but many of the structures they built appear to have been unfinished, suggesting that either they began settling the planet just before they were wiped out, or that the Protheans' attempts at building their settlements were stymied by the native wildlife.

Whatever the reason, Zarr showed no signs of sentient life until centuries later, when the common ancestors of the lirrax and the taaria discovered fire and began to use the illumination that it provided to explore the Prothean ruins. There, they discovered the technology that the Protheans left behind, and a debate was sparked. According to taaria historical records, there were ten tribes of ancestors, and they disagreed about whether to try and utilize the old Prothean machines or leave them alone. Eight of the tribes favored activating the machines, arguing that the benefits might very well outweigh the risks. The other two tribes, however, realized that once they activated the machines, their civilization would become set upon a path that was not of their own making. Ultimately, the eight tribes claimed majority rule and activated the machines, and within a century, they had jumped from a Stone Age into an Iron Age. The other two tribes fled for the deserts, where they slowly evolved into the taaria (a name, inherited from the ancestral language, which translates roughly to "pause", though the it has become the lirrax word for "dead end".) Those who chose to stay in the ruins became the lirrax ("queen and king", from a much longer ancestral phrase - "any woman can be a queen, and any man can be a king.")

Over the centuries, lirrax society continued to evolve, eventually reaching a level of technological sophistication equivalent to mid-21st century humans. However, in 540 BCE, the lirrax underwent a mass mutation event in which a large part of the male population experienced a sudden and alarming rise in their testosterone levels - essentially an epidemic of "roid rage". Scientists tried for years to find a cure, and when impatient regional governments began to undertake drastic action, riots broke out, and lirrax civilization collapsed.

Meanwhile, in the deserts, the taaria slowly and cautiously developed. They observed their former brethren's technological advances and tried to work out for themselves how to reproduce the new technology. They experienced the same sensations that overcame the lirrax in 540 BCE, but did not suffer the same social breakdown.

Travel advisory
Lirrax raiding parties have been known to use equipment that seeks out their prey based upon hardsuit energy signatures. Visitors to the planet are advised not to wear hardsuits while on the planet's surface.

Behind the scenes
"Zarr is basically one enormous tribute/parody to the "sword and planet" stories made popular by Edgar Rice Burroughs (and later, George Lucas and, to a lesser extent, John Norman.) The taaria are somewhat analoguous to Burroughs' Green Martians, while the lirrax were inspired in part by Norman's Kurii."

- Gnostic