Subsistence change in Iron Age to Tubo-period western Xizang: A stable isotope study from Phiyang Dunkar

Abstract

The Phiyang Dunkar cemetery in western Xizang was in use from approximately 8th century BCE to the 10th century CE. Human skeletal remains from this site provide crucial evidence for understanding subsistence strategies in this high-altitude environment. We conducted stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis on bone collagen from 16 human and 23 fauna remains, spanning four chronological phases: Phase I (8th-4th centuries BCE), Phase II (4th-1st centuries BCE), Phase III (1st-6th centuries CE), and Phase IV (7th-10th centuries CE). Results show that both humans (mean δ¹³C: −17.4 ± 0.4‰) and animals (mean δ¹³C: −17.8 ± 0.9‰) relied primarily on C₃-based resources, while elevated human δ¹⁵N values indicate significant animal protein consumption. While dietary patterns remained stable from Phases I to III, a marked shift occurred in Phases IV, characterized by lower δ¹³C and δ¹⁵N values, signaling increased dependence on C₃ foods and reduced animal protein intake. By integrating isotopic data with paleoclimatic, mortuary, and historical evidence, we propose that this shift was driven by a combination of intercultural exchange, climatic variability, and political change. During Phase IV, communities supplemented their traditional pastoral and foraging economy with intensified crop cultivation, demonstrating the adaptive capacity of high-altitude societies to ecological and sociopolitical pressures.