The upper Ili Valley in northwest Xinjiang is a crucial place for the study of early interactions between the Eurasian Steppe and northern China. This paper presents scientific analytical results and examines the use and production of copper alloys in the region with regard to the transregional exchange of materials and technology. The substantial proportion of unalloyed copper and clear drop in tin concentrations in the bronze samples from the Iron Age indicates the decrease of tin usage compared with the Bronze Age. The shift between the Bronze and Iron Ages can also be seen from the lead isotope results. The changes of the material (alloys) and metal source(s) between the Bronze and Iron Ages in the upper Ili Valley imply movements of objects, raw materials and related technical practises.