The Proto-Tethys Ocean has played a significant role in the geological history of Earth. However, ongoing debates persistregarding the timing and polarity of its early subduction. Volcanic rocks associated with iron deposits in the BulunkuoleComplex, West Kunlun Orogen, offer insights into both the complex’s formation age and Proto-Tethys evolution. This studypresents newly obtained zircon U–Pb age data (~536 Ma) along with comprehensive whole-rock major and trace element andSr–Nd–Hf isotope analyses of these volcanic rocks. Our dataset implies that the Bulunkuole Complex partly formed in theearly Paleozoic rather than entirely in the Paleoproterozoic, as previously suggested. Geochemically, the volcanic rocks exhibitenrichments in large ion lithophile elements and light rare earth elements, along with depletions in high-field strength elements.They also display elevated initial 87Sr/86Sr values (0.71093, 0.72025) and negative εNd(t) values (−5.13, −6.18), classifying them ascontinental arc volcanic rocks. These geochemical fingerprints, complemented by zircon εHf(t) values (−12.7 to −1.6), indicatethat the parental magmas of the volcanic rocks were produced by partial melting of the lithospheric mantle wedge, whichhad been metasomatized by subducted sediment-derived melts. The available data, in conjunction with previously publishedfindings, strongly suggest that the Proto-Tethys Ocean subducted southward prior to approximately 536 Ma due to the assemblyof Gondwana. Subsequent slab rollback may have resulted in a crustal thinning of 9–25 km during 536–514 Ma. Further shifts insubduction dynamics led to the transition from high-angle subduction to either normal or low-angle subduction, facilitating theformation of a thicker crust ranging from 39 to 70 km between 514 and 448 Ma. This study, therefore, provides valuable insightsinto the early evolution of the Proto-Tethys Ocean and contributes significantly to our understanding of the tectonic history ofthe West Kunlun Orogen.