At the end of the 16th century AD, the Amazon forest was occupied by around 10 million Indigenous peoples. They had lived there since the Terminal Pleistocene, but by the early 1700s about 90 percent of them had perished. Over the course of millennia, those people had substantially transformed the Amazon. Transformations happened on such a scale that one is forced to accept that the Amazon is as much cultural as it is natural. In addition to ancient orchards embedded in the forest and patches of rich fertile soils, one finds traces of earthen architecture in the form of ditches, roads, embankments, and mounds. Such built spaces are directly connected to people’s lives today, even when there is no direct link between peoples of the past and the present. In the Amazon, any effective approach to understanding the deep past must look for traces that go beyond the realm of the materiality of the archaeological record. This may be the case in other tropical settings still poorly known to archaeologists, such as Central Africa and Melanesia. Where forests are ruins, a comparative global history may have to be a comparative natural history as well.