Ch'sis is a system in the Cimaron Region of the Peco Arm of the Milky Way Galaxy.
Its primary planet is also named Ch'sis, and is claimed by the Athal, who own all mineral rights.
From the Books: "Ashattoo wondered – what was the chance, on this world of all worlds? They’d harvested modest amounts of gaseous hydrocarbons, enough to make the operation almost worth the expense of the 100-cycle lease, and the Mining Guild didn’t sell leases on worlds that had even a minor possibility of being profitable with ease. More than 10,000 cycles ago, Ch’sis had been a veritable treasure trove of various rare gases. Despite the remnants of the white dwarf in the center of its system, though, Ch’sis wasn’t found to possess the rarest of the rarest of the rare – a gas so rare it was usually only found in the rocky core of a former gas giant. Ch’sis had been such a planet and had barely survived the supernova that reformed it. After the gaseous atmosphere had been blasted away by the shockwave of its star exploding, only a planetoid less than four thousand miles wide remained." - Cartwright's Cavaliers, p. 17-8.