Zchol was the fourth planet in the Sidianial star system in the Orion Neutrality Area in the Alpha or the Beta Quadrant. It was the only class M planet in its system, and it had no moons. It was home to an Orion Colony.
Five major races have all called Zchol their ancestral home at one time or another, each conquered by the next. After the original inhabitants, the Athan invaded and brought in a small number of Orion slaves. The Athan were in turn conquered by the Shani, who were similarly conquered by the Kezt. The Orion slaves survived each invasion, and were dominated by all three races, but steadily grew in number.
The Kezt were members of the Nine Worlds Confederation, founded circa 700 BCE (that is, 800 years after 1508 BCE, reference stardate −35/0811). The Nine Worlds sought to limit Orion freedoms and have greater controls over the slaves. When the Orion War for their liberation broke out between 94 to 56 BCE (reference stardate −20/94 to −20/56), the Orion slaves rebelled. They sabotaged the Nine Worlds Confederation 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.
With the conclusion of the war and the golden age of the New Days, 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 Zchol's multiracial population was decimated and many fled. Though trade was cut-off and the population reduced, the Orions of Zchol were now free of outside interference.
Looking inward, they healed their social ills and developed the world and its resources. Finally, by the mid-23rd century, Zchol had become a model Orion Colony, peaceful and prosperous with a population of 3.1 billion people. The Zchol Planetary Congress (modeled on the Botchok Planetary Congress governed the world.
All this came to a crashing halt with the end of the Four Years War. The Federation's Rigel Demilitarized Zone Commission formed the Orion Neutrality Area, closing the borders, and then resettled nearly 2 billion refugees on Zchol. They brought their own conflicts, weapons and needs for aid, and planetary government collapsed under the weight of their demands.
By the late 23rd century, Zchol was a highly chaotic, unpredictable and fractured world, divided up between 22 ruling families and other political factions, all squabbling with each other and sometimes fighting over various cities and regions. The Federation, Starfleet and the Botchok Planetary Congress worried that several Zchol political factions would spread their radical causes and conflicts to other worlds, such as Ing and Morales, which lay in Federation space.
Zchol had a cool temperate climate, a class M terrestrial atmosphere and a 23-hour-long day. It had a total surface area of 648,729,120 square kilometers and, with 30% land mass, a total land area of 194,618,730 square kilometers. About 42% of its makeup was normal metals, 23% was radioactive elements, 15% was gemstones, 9% was industrial crystals, and 5% was special minerals. (FASA RPG module: The Orions: Book of Common Knowledge)