Oristrom was an Unknown Regions planet located in the eponymous system. The homeworld of the strong–willed Stromma species, the world was controlled by the Stromma council, an organization that led all Stromma planets.
In 0 ABY, during a battle in the Poln system of the Outer Rim Territories alien warlord Nuso Esvas gloating, which stated the Stromma's fate if they chose to join his realm, was shared by Galactic Empire Senior Captain Thrawn through the DeepWater-class light freighter Lost Reefs modified comm unit with the Stromma. After Esva learnt of that, he promised Thrawn that once he finished off Thrawn's forces, he would travel to Oristrom and turn the Stromma into "useful" tools. However, his fleet was destroyed and he did not destroy the senior captain.
At some point after the battle in the Poln system, the Stromma engaged Esva's warriors, the Chosen, on the Stromma homeworld. The Stromma had the upper hand; however, Esva assumed personal command and turned the tide of the battle. The Empire of the Hand, a confederation in Wild Space allied with the Stromma, defeated the warlord's forces thanks to Grand Admiral Thrawn's obsession with art.