El Niño–Southern Oscillation has been treated as a disruptor of environmental and socioeconomic equilibrium both in ancient times and in modern-day Peru. Recent work in the coastal desert plain, known as the Pampa de Mocan, challenges this view by demonstrating that prehispanic irrigation systems were designed to incorporate floods and convert them into productive waters. Archaeological investigations in this landscape reveal a 2,000-y history of floodwater farming embedded in conventional canal systems. Together with a pollen record recovered from a prehispanic well, these data suggest that the Pampa de Mocan was a flexible landscape, capable of taking advantage of El Niño floodwaters as well as river water. In sharp contrast to modern-day flood mitigation efforts, ancient farmers used floodwaters to develop otherwise marginal landscapes, such as the Pampa de Mocan, which in turn mitigated risk during El Niño years. These archaeological data speak to contemporary policy debates in the face of increasingly intense and frequent natural disasters and question whether El Niño Southern Oscillation events should be approached as a form of temporary disorder or as a form of periodic abundance.

Here we present the first 14C ages for the Ascope Canal System (ACS), a large pre-Hispanic hydraulic network in the Chicama Valley on the north coast of Peru. Composed of multiple alignments that irrigated areas north of the river, our results indicate that the ACS was constructed and operated in the Late Intermediate Period, ca. A.D. 1000-1400. This overlaps in time with the Chicama-Moche Intervalley Canal that diverted water on the south side of the Chicama River and extended to the city of Chan Chan. Conservative estimates of discharge capacity indicate that the canals combined would have exceeded stream flow in the Chicama River half of the year. The ACS appears to have functioned for several centuries and would have been in direct competition with the Intervalley Canal with, apparently, insufficient water for both systems and other Chicama Valley canals during most of the year. This study underscores the complexities of understanding the operations and histories of irrigation systems in complex societies.

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The arid desert coast of northern Peru has traditionally been viewed either as existing in stasis, or as experiencing punctuated change from sudden flood events, followed by a return to system equilibrium. Despite these environmental extremes, the region was home to agriculture-based societies for millennia, and the success of these farming systems is considered an early example of irrigation technology transforming marginal landscapes. However, a closer examination of the long-term human-environment history of the Chicama Valley, one of the largest valleys in the coastal region, demonstrates that this landscape is the product of protracted interactions across at least three systems: the local environment, El Niño Southern Oscillation (ENSO), and farming. Here, El Niño floods, typically considered high-risk events, are fundamental to local biodiversity and renewal, resulting in a desert ecosystem that is both robust and elastic. The prehispanic farmland known as the Pampa de Mocan (1100BC–AD1460), is presented as a case study to observe the co-evolution of agricultural technology and an ENSO-hyper-arid environment. This ancient farming system developed the capacity to toggle between sudden floodwater inputs and periods of water scarcity. Alongside water and soil conservation practices, prehispanic agriculturalists implemented technologies that were designed to mitigate El Niño flooding and incorporate its byproducts to supplement available resources. The convergence of these interacting systems on the Pampa de Mocan offers new insights into the role of risk in building resilience.

Animals were central elements in many early state political economies. Yet the roles of livestock in building and financing the state generally remain under-theorized, particularly in comparison with other major elements such as crop intensification and bureaucratic technologies. We compare the political economies of two highly centralized and expansive states—the Inca in the central Andes and Ur III in southern Mesopotamia—through a deliberately animal-focused perspective that draws attention to the unique social and economic roles of the livestock that underpinned both imperial financing and household resilience. Despite important differences in the trajectories of the two case studies, attention to the roles played by animals in early states highlights several underlying dynamics of broader interest including the translation between modes of production and accumulation, the interplay between animal-based mobilities and territorial integration, and the functions of livestock in state regimes of value and political subjectivity.