(Phys.org)—The study of ancient civilizations, particularly those that did not leave extensive writing in the archaeological record, is reliant on the evidence of other kinds of material artifacts. And one of the keys to understanding large, complex societies is mapping the circulation of such artifacts. An international research collaborative recently published a study in the Proceedings of the National Academy of Sciences on the production and circulation of artifacts in the south-central Andes during 400 BC to 1000 AD.