1. Collaborative Research Centre for Archaeology of the Silk Roads, Northwest University, Xi’an 710127, China
2. School of Cultural Heritage, Northwest University, Xi’an 710127, China
3. Ningxia Institute of Cultural Relics and Archaeology, Yinchuan 750001, China
4. Department of Anthropology, Harvard University, Cambridge, MA 02138, USA
5. Beijing Institute of Archaeology (Beijing Institute of Cultural Heritage), Beijing 100009, China