Precursors were humanoid, highly intelligent creatures with five digit hands and similar physical capabilities to an average human, though their internal organs were different, presumably accomodated to their homeworld's environment and evolutionary path. Their kind crash-landed in Australia shortly after the impact of a massive U-259 asteroid in the area we today call the Black Valley, probably attempting to salvage said asteroid for orbital mining and transport. Blessed with extremely robust survival and manufacturing technology, as well as a militarised society, the precursors were able to survive in Australia for far longer than the environment would have otherwise allowed them to. However, the presence of the sentient ents and their proficiency at genetically engineering monsters to hunt down precursor settlements forced them to partake in a final act of vengeance; around 37 technopsychic warpstone fusion bombs were detonated all over the continent, "reducing" much of the U-259 in the environment into U-238, the particles released irradiating everything. Both civilisations went extinct shortly after. Precursors were capable of breathing in Earth's atmosphere, albeit with some difficulty, and could consume much of its flora and fauna.