This chapter treats the period during which great states appeared in the Andes and urbanism there reached its apex. The information is basically archaeological, although important data also come from sixteenthcentury documentary sources. The first part of this process is known as the Middle Horizon (c. C.E. 560–1000); the term “horizon” signals the spread of a typical culture and social organizations across multiple regions. The second is called the “Late Intermediate Period” (eleventh to fifteenth centuries); the term “intermediate” indicates a period of diverse, regional developments between horizon cultures (see Map 6.1). Like the widely diffused culture of Chavín in remote antiquity whose traces make up the Early Horizon (see Chap. 5), the Middle Horizon showed farflung unifying tendencies. Some of them set precedents for a third unification in the Late Horizon, or Inka era (fifteenth to sixteenth centuries). Like the Early Intermediate that followed Chavín, the Late Intermediate was an era of accentuated variety, sometimes carrying forward and reworking already-ancient cultural legacies.

THE PRECURSORS

During the fourth, fifth, and sixth centuries C.E., each region took on a particular social form, with characteristic linkages among valleys and river basins, different levels of complexity in social and economic organization, and unique ways of managing territory. Clearly the variability of the environment constituted an important factor in this process of regionalization.

The mid–sixth century witnessed an era of serious climatic alterations in the Andes, which could have led to displacements of populations and to nutritional and social crises of varying magnitude. It seems that in Cusco and the Lake Titicaca area rains fell almost 30 percent below normal levels for about 30 years, between the years C.E. 562 and 594. These conditions undoubtedly affected the normal development of productive activities throughout the entire territory, possibly explaining the general tendency toward changes and dislocations in most of the populations of that period. Although paleoclimatic records indicate continual alterations in humidity throughout the whole Holocene – characterized by periods of drought and also by rains that extended over several years – this 30-year stress was exceptionally long and seemingly intense.

In the southern sierra, two processes that seriously affected the Andes as a whole emerged, although evidently not as direct consequences of such natural events. First was the formation and development of a state that expanded from the southern sierra – modern Ayacucho – throughout the entire territory of the Central Andes.