The Kezt were a race that existed thousands of years ago.
The Kezt were one of the strongest civilizations active near Rigel. After 700 BCE (that is, 800 years after 1508 BCE, reference stardate −35/0811), the Kezt joined the Nine Worlds Confederation, a significantly powerful alliance with eight of the strongest neighboring civilizations. Along with the rest of the Nine Worlds, the Kezt were signatories to the Treaty of Kammzdast, which governed the use of Orion slaves.
They invaded the planet Zchol and conquered its previous conquerors, the Shani. The Kezt also took possession of the Orions already on the world. They came to consider Zchol their new ancestral home.
Following the Taunpymi Incident of 111 BCE (stardate −21/1105), in which Orion links with pirate attacks were revealed, Nine Worlds member races like the Kezt came to believe that the Orions had gained too many rights and too much independence for a slave-race. They even grew jealous of their strangely fortunate and influential slaves. In response, they demanded absolute adherence to the terms of the Treaty of Kammzdast and other laws and regulations, no matter how old and out-of-date, and created new ones. With the success of these measures, the Nine Worlds Confederation moved to make them permanent, and held the 187th Rigel Conference on Rigel IV on 14th July 95 BCE (stardate −20/9507.14). There they intended to issue the Ultimatum of the Nine Worlds, a list of prohibitions that restricted Orions from participating in any commercial activities in or out of the Rigel system.
The resulting rebellion triggered the Orion War. Rebellion erupted across Zchol and the rest of Nine Worlds, and Orions everywhere sabotaged the enemy war effort, kept their ground forces occupied and hindered their space efforts, no matter the risk to themselves. Zchol suffered particularly heavy fighting in a conflict known as the Agony of Zchol. However, unwilling to give up the valuable resource of Orion labor and surrender their claims and privileges, the Kezt and the rest refused to give in. It was thought that a little war would cow the slaves, and it would still cost less than doing without them. Thus, the war went on for thirty-seven long years.
When it was over on February 13th, 56 BCE (stardate -20/5602.13), the Orion's former masters had nothing but animosity for them after four decades of war. They despised the idea of treating the Orions as equals. They embargoed trade with the Orions and treated them with suspicion, but Orion hard work and enterprise and the ex-slavers' continued reliance on them turned the tables. During the New Days of the Orions, the Kezt and other races grew excessively wealthy, self-indulgent and utterly dependent on the Orion economy. Zchol rebuilt, but it was never able to heal all the scars left by the Agony. Then the Reverse came, bringing with it the century-long Purge, in which the Kezt and the rest of Zchol's multiracial population was decimated and many fled, leaving only the Orions (FASA RPG module: The Orions: Book of Common Knowledge).