Plants and insects have been the main sources of natural dyes in the past and have been utilized for several millennia. A large number of well-preserved textiles unearthed from archaeological sites has provided us with opportunities to understand systematically the use of natural dyes in Northwest China. In the present study, dye analyses of about 400 samples from archaeological textiles dating from the 17th century BCE to the 10th century CE were carried out by high performance liquid chromatography coupled with a diode array detector and a mass spectrometric detector (HPLC-DAD-MSD), revealing a 2500-year history of natural dyes in Northwest China. At least 16 dyes were used to color the archaeological textiles. Of these, Rubia tinctorum is considered to be the earliest dye source in Northwest China, but the presence of Porphyrophora species in Subeixi textiles (the 5th-3rd centuries BCE) suggests that the early transmission of the steppes culture from the south of Siberia to the Turpan Basin occurred in the early Iron Age. The geographical origins of the dyestuffs identified in Mogao Grottoes textiles indirectly indicate that the four most influential cultures--Chinese, Hellenic, Islamic and Indian--in Eurasia all converged at Dunhuang in the Tang Dynasty.