Daibazaal was the home planet of the Galran race and the birthplace of Emperor Zarkon. It was destroyed by King Alfor ten thousand years ago after the race was evacuated because of a dangerous rift between realties caused by the comet that crashed into the planet - the same comet Alfor used to create Voltron.
Much of Daibazaal's history is unknown. 10,000 years ago, the planet was an empire ruled by Zarkon, who had forged a warrior's bond and alliance with King Alfor, Trigel, Gyrgan, and Blaytz. During a meal amongst comrades, a comet of unique trans-reality ore crashed into Daibazaal, leaving a rift between realities in its wake. Alfor had the comet removed and taken to Altea to study it, leaving behind Altean alchemists such as Honerva to study the rift. Zarkon immediately fell in love with Honerva and married her.
Alfor soon created the Voltron Lions from the ore. In the pursuit of knowledge, Honerva lured an unusual creature of darkness from the other side of the rift, causing a swarm of darkness to follow and attack. This forced Zarkon and his alliance of warriors to become the original Paladins of Voltron to defeat the darkness, beginning the legend of the heroic robot. Unafraid of the danger, Zarkon and Honerva continued researching the trans-reality rift for many years in an obsessive pursuit of Quintessence as it weakened the very foundation of Daibazaal, despite Alfor's pleas to close the rift forever.
Once Zarkon and his wife became obsessed with the Quintessence found in the reality rift, the exposure damaging Honerva's health, Zarkon attempted to bring Honerva into the rift using Voltron so he could save her with the Quintessence and darkness within. His fellow Paladins were not aware of his trickery until it was too late. The overexposure seemed to kill both he and his wife when they recklessly left the safety of Voltron inside the rift.
But after Alfor held their funeral and destroyed the evacuated Daibazaal to erase the reality rift, Zarkon and Honerva awakened, changed and corrupted by their ordeal. Zarkon flew into a rage at Alfor and the Alteans for the loss of the rift, sparking a war and the beginnings of the Galra Empire.