Yuuzhan'tar, situated in a galaxy far removed from the primary galaxy, was a living, sentient, and extra-galactic planet. This world served as the original homeworld for the Yuuzhan Vong species and was characterized by a substantial asteroid belt encircling its equator. The Yuuzhan Vong also referred to their planet as "the homeworld." A cataclysmic ancient war led to its demise, compelling the Yuuzhan Vong to abandon their original galaxy.
In the Yuuzhan Vong language, Yuuzhan'tar translates to "Crèche of the Gods," as the living planet served as a representation for their many deities.
At some point in their past, the Yuuzhan Vong from beyond the galaxy found themselves under attack by a race of droid entities known as the Abominor. These droids were engaged in conflict with another droid species of the time, referred to as the Silentium. The Yuuzhan Vong's living world played a role in their war against these invading droids, granting them the ability to construct "living," organic weapons from living (or previously living) materials. However, as the conflict progressed, the Yuuzhan Vong became increasingly violent and prone to warfare. Eventually, they triumphed over their adversaries, forcing both droid factions to exit their galaxy.
After the war with the droids, the Yuuzhan Vong developed resentment and strong dislike for anything they considered inorganic. Consequently, they initiated a campaign to rid their galaxy of all mechanical technology. They seized control of much of their own galaxy, either eliminating or enslaving the populations they conquered. Among those they subjugated were the reptilian Chazrach, who were forced to serve as Yuuzhan Vong slave soldiers. However, the Chazrach faced a similar fate to other races conquered by the Yuuzhan Vong. Any race other than the Yuuzhan Vong was automatically deemed inferior, abominable, or blasphemous, and were placed below the lowest ranks of the Yuuzhan Vong's rigid caste system.
With control over a large portion of the galaxy, the various Domains became divided and turned against one another, leading to the destructive Cremlevian War. During this war, much of their galaxy was destroyed, including their home planet, Yuuzhan'tar. However, the planet produced a seed that later became Zonama Sekot.
Cut off from their original connection with their homeworld, the Yuuzhan Vong were severed from the Force, causing them great suffering. As a result, they came to view pain as the only means of regaining that connection and began practicing body modifications on themselves. In place of their homeworld, the Yuuzhan Vong established several deities to govern nearly every aspect of their civilization.
Towards the end of the war, Steng emerged as the first Warmaster. A rival Warmaster, Yo'gand, developed the Yo'gand's Core tactic, which he used to destroy the planet Ygziir and its moon. The destruction of Ygziir led to Steng's death and the end of the war. Eventually, Yo'gand unified the Domains into a single socio-political entity and became the first Supreme Overlord of the Yuuzhan Vong.
However, with much of their galaxy devastated, the Yuuzhan Vong embarked on a long journey to another galaxy in search of a new home. For millennia, the Yuuzhan Vong were forced to travel through the Intergalactic Void in their enormous, organically-constructed worldships, a period during which they nearly destroyed themselves. Violence and competition were ingrained in their society, and without an external target, they often turned their aggression inward. Although there were no large-scale wars like the Cremlevian War, the Domains continued to compete for the favor of the Supreme Overlords.
In the endnotes for The New Essential Guide to Droids by Daniel Wallace, the conflict between the Silentium and the Abominor is strongly suggested as the primary cause of the Yuuzhan Vong's technophobia.