Oon Tien was a planet located in the Oon Tien system in the Kathol sector of the Outer Rim Territories. Oon Tien was connected by hyperspace travel routes to the Torize, Kolatill, and Corjain systems. Torize was fourteen hours travel from Oon Tien, Kolatill was nineteen hours distant, and travel to Corjain took eleven hours. A wet and mountainous planet, Oon Tien was the homeworld of the Jarell species. As the world was integrated into the economy of the Kathol sector, it became a major agricultural and manufacturing center. After coming under Imperial rule, the planet was home to the largest shipyard in the sector as Moff Kentor Sarne—ruler of the Kathol sector both as an Imperial official, and later, as a warlord—had three stardocks established in orbit. As the planet was a major maintenance hub for his fleet, Sarne protected the Oon Tien system with at least two dozen IPV-1 System Patrol Craft, a full wing of TIE Fighters, and hundreds of proton mines.
The native Jarells established a primitive society on the planet based around feudal monarchic city-states, and had developed basic metalworking skills when Galactic Republic colony ships discovered the system around 292 BBY. Human colonists settled on the planet, building several communities and existing side-by-side with the native Jarell city-states. The Jarell monarchs began trading precious gemstones and periods of indentured servitude of their young for weapons and high technology from the Human settlers. The traded equipment assisted the Jarells in a series of internal revolutions that changed Jarell society, although the conflicts never threatened the Human settlements.
For several decades before the Battle of Yavin, Oon Tien became more integrated into the Kathol sector, with several large manufacturing complexes being established on the planet. The world also developed an extensive agricultural industry. When Oon Tien came under the control of the Galactic Empire, Moff Kentor Sarne appointed Governor Manon Flint to command the system. Sarne established three orbiting stardocks in the system, each capable of servicing and repairing capital ships up to 300 meters long. The docks were the main maintenance facilities for Sarne's forces, and were the largest shipyards in the sector. Oon Tien became part of Sarne's holdings when the Moff broke from the Empire in the wake of the Battle of Endor in 4 ABY and declared himself a warlord.
Following the fall of the sector capital Kal'Shebbol to New Republic forces in 8 ABY, Sarne was forced to retreat into the Kathol sector. Sarne ordered Governor Flint to hold the docks at all costs, or destroy them if the New Republic managed to invade the system. As the New Republic spread its influence throughout the sector, Oon Tien would prove to be one of the most troublesome planets as it was too heavily defended by Imperial loyalists to fall easily or quickly.