The Th'irus system existed in the region known as Wild Space. It was the location of the planet called Th'irus, which was the native world of the sentient species known as the Th'iruckai.
The foundation for the Th'irus system was the planet Th'irus, which first appeared in the Star Wars Gamemaster Screen. However, The Essential Atlas presented an alternate spelling, "Thi'rus." This error was subsequently addressed and corrected through an update to the Star Wars: The Essential Atlas Online Companion.