A total of 33 ancient glass beads unearthed from the Kizil reservoir cemetery and Wanquan cemetery in Xinjiang are studied using Raman spectroscopy, scanning electron microscopy with energy-dispersive spectrometry (SEM–EDS) and other methods. The detailed study of the glassy matrices, the crystalline inclusions and the microstructural heterogeneities for these glass beads has revealed some valuable information to help in the understanding of their possible manufacturing technology and provenance. At least two different types of glass were present in the two cemeteries. For the first time, antimony-based colourant/opacifier—for example, Pb2Sb2O7 or CaSb2O6—was systematically identified in some beads of plant-ash type soda–lime glass dated to about 1000–500 bc. The limited number of potash glass beads from the Kizil reservoir cemetery, which were dated to about 500–300 bc, used tin oxide as an opacifier. The diverse resources of the soda–lime and potash glasses indicate the existence of a complex trade network between China and the West much earlier than the Western Han Dynasty.