The Late Intermediate Period in the south-central Andes (AD 1000–1450): Key problems in chronology

Abstract

The Late Intermediate Period (LIP, cal AD 1000–1450) in the central Andes is defined as a hiatus after the collapse of Tiwanaku and Wari, expansive state polities of the Middle Horizon (cal AD 600–1000), and before the domination of the Inca empire in the Late Horizon (cal AD 1450–1532). The LIP is often characterized as a unit, but major developments took place within this long period, including diasporic migrations and the new colonization of some regions, demographic change, intensified conflict, large-scale adverse climate episodes, and changes associated with the onset of Inca expansion. Here we make a preliminary attempt to clarify the chronology of these developments. A database of published and new radiocarbon dates is compiled for the south-central highlands and coastal valleys in order to model overall and subregional demographic trends using an updated “dates-as-data” cumulative kernel density estimate (CKDE) approach, and to examine specific LIP phenomena in two subregions. Our results indicate major demographic change including 1) substantial population growth beginning in the 13th century, 2) a marked 14th-century population surge in most, but not all, subregions included here, 3) evidence of population decline in several subregions during the same intervals when neighboring populations are expanding. Population growth was associated with intensified violence and increased physiological stress in the upper Nasca drainage. In the altiplano of Peru and Bolivia, population growth accompanied the rise of defensive hillforts and monumental cemeteries. Our date models also indicate a more complicated terminal LIP in the altiplano, with the height of classically “LIP” societies overlapping with early evidence for imperial Inca presence. This paper highlights the ways that more refined chronology can make advances in our understanding of a turbulent post-collapse era in the Andes.