The Tzun were a spacefaring species by at least 23,000 BCE. Shortly after developing space travel, they fought the Darklings of Yuggoth, which corrupted their DNA. They perfected genetic engineering and began integrating new species into their Confederacy by combining their DNA with theirs.
This resulted in the creation of three sub-species of Tzun. There were the pure Tzun, who were not genetically modified; the small gray S'Raph with big heads and black eyes, which had their visual perception expanded to see into the infrared and ultraviolet; and the Ph'Sor, whose DNA was combined with the natives of the planet they were colonising.
In 2172, the Tzun attempted to conquer the Veltrochni. (PROSE: First Frontier) Though the Tzun were successful at the beginning, as the war carried on the Veltrochni packs joined forces and fought back. They drove the Tzun off, destroyed many of their colony planets and effectively collapsed the entire confederacy. The Veltrochni became renowned for their power after this. (PROSE: The Dark Path) After this, the Veltrochni gained the Tzun's advanced weaponry. (PROSE: Mission: Impractical)