Until recently the human race only decided to classify and describe species that have been known to humankind for a lot longer. I’d only entertain lack of evidence of species being in a location as evidence that such a location wasn’t part of its range if some less dominant culture that existed in that location prior to the colonial version of naturalism created a “comprehensive” list of local species (excluding mythological creatures and microbes). We can be fine with not knowing if something was native or introduced otherwise because it’s not really that important unless there is evidence that that something is causing damage to the ecosystem.