A bioarchaeological analysis of the effects of the Xiongnu empire on the physical health of nomadic groups in Iron Age Mongolia

Abstract

The Xiongnu Empire (c. 200 BC – AD 100) was the first instance of imperial level organization by nomadic groups of the Mongolian steppe. Over a century of historical and archaeological research has produced a large body of scholarship on the political, military, and sociocultural structures of Xiongnu society. This study adds to the growing body of recent bioarchaeological research by using multiple lines of evidence to address the impacts of empire formation on the physical health of those who lived under the influence of Xiongnu rule. Models of Xiongnu empire formation posit stable access to Chinese agricultural goods and reduction in violent conflict as major motivating factors in establishing imperial-level organization among Mongolian nomadic groups. By gathering data from the skeletal remains of 349 individuals from 27 archaeological sites and analyzing the frequency of 10 dietary and health indicators, this study addresses these claims. The Xiongnu imperial expansion and administration resulted in the movement and/or displacement of nomadic groups, consequences that are documented in Chinese historical texts, but its impact on population structure is poorly understood. Craniometric data collected from this skeletal sample were used to conduct a model-bound biological distance analysis and fit to an unbiased relationship matrix to determine the amount of intra- and inter-group variation, and estimate the biological distance between different geographic and temporal groups. This skeletal sample includes individuals from 19 Xiongnu-period sites located across the region under Xiongnu imperial control. Individuals from eight Bronze Age sites in Mongolia were included to establish pre-Xiongnu health status. One agricultural site within the Han empire, contemporaneous with the Xiongnu, was included for comparison. The results of this study indicate that Xiongnu motivations for creating a nomadic empire were considerably more complex than current models suggest. Although historical texts document that the Xiongnu received agricultural products as tribute from China, dietary markers indicate the Xiongnu diet was more similar to that of their Bronze Age predecessors than to their agricultural Han neighbors. The movement of people across the Mongolian steppe during the Xiongnu period created a more phenotypically homogeneous population structure than that of previous Bronze Age groups.