Lidar reveals pre-Hispanic low-density urbanism in the Bolivian Amazon.

Archaeological remains of agrarian-based, low-density urbananism 1-3 have been reported to exist beneath the tropical forests of Southeast Asia, Sri Lanka and Central America 4-6 . However, beyond some large interconnected settlements in southern Amazonia 7-9 , there has been no such evidence for pre-Hispanic Amazonia. Here we present lidar data of sites belonging to the Casarabe culture (around AD 500 to AD 1400) 10-13 in the Llanos de Mojos savannah-forest mosaic, southwest Amazonia, revealing the presence of two remarkably large sites (147 ha and 315 ha) in a dense four-tiered settlement system. The Casarabe culture area, as far as known today, spans approximately 4,500 km 2 , with one of the large settlement sites controlling an area of approximately 500 km 2 . The civic-ceremonial architecture of these large settlement sites includes stepped platforms, on top of which lie U-shaped structures, rectangular platform mounds and conical pyramids (which are up to 22 m tall). The large settlement sites are surrounded by ranked concentric polygonal banks and represent central nodes that are connected to lower-ranked sites by straight, raised causeways that stretch over several kilometres. Massive water-management infrastructure, composed of canals and reservoirs, complete the settlement system in an anthropogenically modified landscape. Our results indicate that the Casarabe-culture settlement pattern represents a type of tropical low-density urbanism that has not previously been described in Amazonia.