Modeling environmental variability and network formation among pastoral nomadic households: Implications for the rise of the Mongol Empire

Abstract

We use agent-based computer simulation to test the effect of environmental conditions (available biomass/carrying capacity and environmental risk) on the development of wealth inequality and patron-client herding networks in nomadic pastoral economies. Our results show that 1) wealth inequality reaches very high levels when carrying capacity is high and risk is low, and 2) patron-client contract herding networks increase in size and duration when carrying capacity is high and risk is low. We compare empirical data from the Mongol (1206–1368 CE) and Xiongnu (209 BCE– 48 CE) empires with simulation results to develop an explanatory mechanism for the apparent correlation between nomadic empire creation and positive environmental conditions. We argue that the internal dynamics of nomadic pastoral societies are sufficient to produce high degrees of inequality and hierarchical herding networks. Nomadic empires are more likely to form during key periods of increased biomass and decreased environmental risk.

Central Mongolian lake sediments reveal new insights on climate change and equestrian empires in the Eastern Steppes

“…Sustained humid conditions likely enabled the expansion of fertile grasslands and thus, increased ecosystem carrying capacity 14 , 17 , 61 — allowing to raise larger numbers of livestock and horses for both meat and dairy production 9 , 11 . Particularly in the dry and seasonal steppe environment, domestic livestock herds experience “economies of scale” — wherein smaller herds are more vulnerable to loss from disease, predation, or weather, and larger herds are more resilient 62 .…”

“…Particularly in the dry and seasonal steppe environment, domestic livestock herds experience “economies of scale” — wherein smaller herds are more vulnerable to loss from disease, predation, or weather, and larger herds are more resilient 62 . With productive areas distributed unequally across the landscape, and some herders inevitably subject to disaster and loss, periods of environmental productivity appear to encourage the formation of larger steppe social networks 17 . As the key engine of preindustrial transport and warfare in Eurasia, horses directly impacted the military and transport capacity of steppe societies, while long military campaigns also often required grazing areas for other livestock 63 .…”

“…For these pastoral empires, extensive and productive grasslands provide the engine for both economic and political power 13 , 14 . Yet, particularly in the dry and harsh steppes of eastern Eurasia, minor climate variations can have large impacts on the water balance, biomass production, and ecosystem carrying capacity 15 – 17 . The close coupling between precipitation and temperature regimes and domestic animal productivity has inspired hypotheses that climate changes may have played an important role for network formation and human history in Central Asia 17 .…”

“…Yet, particularly in the dry and harsh steppes of eastern Eurasia, minor climate variations can have large impacts on the water balance, biomass production, and ecosystem carrying capacity 15 – 17 . The close coupling between precipitation and temperature regimes and domestic animal productivity has inspired hypotheses that climate changes may have played an important role for network formation and human history in Central Asia 17 . While social-economic changes such as the emergence of social inequality in pastoral societies can be well inferred from historical and archaeological records 11 , 17 , 18 , potential climatic controls can only be assessed by high-resolution paleoclimate records, which are currently rare for the Late Holocene in Mongolia.…”

SAGAscape: Simulating Resource Exploitation Strategies in Iron Age to Hellenistic Communities in Southwest Anatolia

“…It provides a formal computational framework that allows a more dynamic approach to complex issues such as the delineation of catchment areas and calculations of carrying capacity. ABM has been successfully applied in archaeological studies on humanenvironment interactions and resource exploitation strategies for topics such as subsistence strategies (Gunaratne & Garibay 2020), risk-decreasing strategies driving social organisation (Shultz & Costopoulos 2019), and resource distribution and exploitation strategies (Janssen & Hill 2016).…”