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

PLoS One. 2019 Oct 10;14(10):e0223677. doi: 10.1371/journal.pone.0223677. eCollection 2019.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Environment*
  • Family Characteristics*
  • Geography
  • Humans
  • Models, Theoretical*
  • Mongolia
  • Regression Analysis
  • Socioeconomic Factors
  • Transients and Migrants

Grant support

This work was supported by the Social Sciences and Humanities Research Council of Canada, Award #: 767-2014-1573 ( The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.