When interplanetary exploration teams first stumbled across Kulthis, they assumed it was incapable of supporting life. The first planet from the Belderone star had a hostile, volcanic surface. Craggy mountains and rocky plains vied for space with seemingly endless volcanic regions. Turbulent and ash-laden, the atmosphere was dangerously hot. Sulphuric fumes from the constant volcanic activity produced a severe greenhouse effect and the noxious air perpetually cast the world in a hazy-yellowish fog. Few sentient species could endure this brimstone atmosphere without thermal protective gear.
Undeterred, these initial exploratory teams began their survey of the surface and found quite a surprise. The rocky terrain was teeming with life! Everything from granite slugs to varactyls roamed mountains and rocky flats alike. Lichens and even fungi could be found in caves while a variety of scrub brush flourished in the occasional oasis. The hot springs which dotted the land provided fresh water and homes for terrestrial and aquatic species adapted to the heat. Many of these species were found to metabolize chemicals both in the water and in the air! Most surprisingly, ruins from ancient settlements were found.
A study of these ruins revealed them to be abandoned colonies many centuries old. Scraps of artwork, and even ancient writings, were found in decaying buildings and caves. While xenolinquists struggled to decode the writing fragments, they were able to determine that these archaic colonists called themselves the "Stenax". While the Stenax themselves would remain a mystery, the remnants of their colonies proved they were highly advanced for their time. They would need to be, just to survive in this environment.
Using these colonial remnants as a model, settlement of Kulthis began in earnest in year fifteen. While the planet's new inhabitants wouldn't venture outdoors without protective gear, they would, and did, mine the planet's deposits of quantum and meleenium to great effect. Kulthis became a major participant in the galactic economy, it's hostile beauty undiminished.