The original Ur-quan were brown in color, and like their two sub-species today, resembled a huge 10-meter long caterpillar with strong tentacles and multiple eyes.
The Ur-Quan evolved on a world far distant from the region of space depicted in the Ur-Quan Masters. Their world was harsh and violent, and they evolved the capacity to dominate that world. They became the top predators of their world. Their only threats were each other, so they had problems getting along with one another. Eventually, they found a way to cooperate with one another, and they formed the rudiments of a civilized society to the best of their abilities.
With a civilized culture driving them, they set out to explore known space. Their forays bore fruit quickly, as they met a race known as the Taalo. The Taalo, being effectively rocks, did not evoke the Ur-Quan's predatory nature. The Ur-Quan could mingle amongst the Taalo without having to fight their biological instincts to kill and dominate. The Taalo belonged to an organization of species known as the Sentient Milieu. Eventually, the Ur-Quan joined the Sentient Milieu, and became a member race in that venerable organization.
Though they were members of the Sentient Milieu, they still had difficulty integrating with other non-Taalo species. As such, they performed the duty to which they were best suited: solitary exploration missions. The Ur-Quan excelled at this task. But, it was in doing so that they brough doom upon not only the Ur-Quan species, but all of the Sentient Milieu as well.
On one expedition to a planet, the Ur-Quan scout discovered the presence of a sentient species known as the Dnyarri. This species had the ability to control the minds of vast numbers of sentient beings. The Dnyarri rapidly conquered the Sentient Milieu. Only the Taalo were immune to the Dnyarri's compulsions. This could not be tolerated, so the Ur-Quan were forced to help exterminate the species they once called friend.
The Dnyarri forced the Ur-Quan to destroy a few other members of the Sentient Milieu over the centuries that they served under Dnyarri compulsion. The Dnyarri visited other forms of pain upon the Ur-Quan, by tampering with them at a generic level. The Ur-Quan were the easiest for the Dnyarri to control, so they wanted to maximize the use of this species. They fractured the Ur-Quan species into two races: the Ur-Quan Kzer-Za, the green Ur-Quan, and the Ur-Quan Kohr-Ah, the black Ur-Quan. The green Ur-Quan would be the thinkers: the scientists and bureacrats. The black Ur-Quan were the workers: the warriors and laborers.
Eventually, an Ur-Quan scientist named Kzer-Za discovered the means by which the Ur-Quan could free themselves from the Dnyarri. Intense pain would prevent any Dnyarri from excercising their mental compulsion. Though it took several years, the Ur-Quan races led the war of liberation and subjugatted the hated Dnyarri.
Then, the two Ur-Quan races met to determine two things: the means by which to punish the Dnyarri and the way to prevent the Ur-Quan from ever suffering under the dominion of another race again. The Dnyarri question was answered quickly: the Ur-Quan stripped them of their sentience at a genetic level, reducing them to mere translation units to allow the Ur-Quan to not have to degrade themselves, as they saw it, by discoursing directly with other sentient species. The second question caused a schism between the Ur-Quan species.
The green Ur-Quan, who had dubbed themselves "Kzer-Za" in honor of the one who had discovered the way to fight the Dnyarri compulsion, suggested what they called the Path of Now and Forever. This would require the Ur-Quan species to subjugate each other species and present them with 2 options: join them as part of their Hierarchy and retain some autonomy, or become a fallow species, trapped on their homeworld beneath an impenetrable slave shield.
Among the black Ur-Quan rose Kohr-Ah, who proposed the Eternal Doctrine. It called for a war-without-end against all non-Ur-Quan species.
Each Ur-Quan race moved to execute their doctrine. The Kzer-Za erected a slave shield around the Faz homeworld, while the Kohr-Ah incinerated the homeworld of the Yuptar. The Kohr-Ah fleet was the first to reach the homeworld of the Mael-Num, the last of the major species that were part of the Sentient Milieu. As the Kohr-Ah began preperations to sanitize the world, a request came from the Mael-Num, asking why they were proceeding on this path. The Kohr-Ah were struck by these words and began to explain. This gave the Kzer-Za fleet enough time to arrive.
The ensuing battle started the first Doctrinal War. A war that the Kohr-Ah almost won. Only the chance discovery by the Kzer-Za of a Precursor Battleship allowed the Kzer-Za to claim victory. But, in victory, the Kzer-Za were magnanimous. They allowed the Kohr-Ah free reign over half of the galaxy, allowing them to practice their doctrine. The Kzer-Za would do the same over the other half. When the two species would meet, they would begin the Doctrinal War anew, with the Precursor Battleship, the Sa-Matra as the prize to the victor.