The paradox of this complex is that the best-preserved material comes from the wrong place. Wood and bone do not survive in the Amazon; the humidity destroys them within a generation or two. They survive extremely well in the hyper-arid oases of the south-central Andes, and above all at San Pedro de Atacama, where burials have yielded snuff trays, tubes, spatulas, pouches and their contents in very large numbers and in good condition.
Constantino Manuel Torres and David Repke assembled that record alongside the living ethnography of the Orinoco basin and the northwest Amazon, where the practice continues. The result is a picture that neither body of evidence gives on its own: a material tradition with real depth in time, carved in styles that can be sequenced, and distributed across ecological zones that had no business sharing a technology unless people and goods were moving between them.
That last point is the one worth taking away. A snuff tray found in a desert cemetery, made of a wood from elsewhere, decorated in an identifiable regional style, and used for a preparation from a lowland tree, is direct evidence of long-distance connection. The forest and the coast and the highlands were not separate worlds, and this small object is among the clearer proofs of it.