MORB from the Indian Ocean has Sr, Nd, and Pb isotope ratios distinct from that of the Pacific and North Atlantic oceans. These Indian MORB isotope signatures (Dupal anomaly) also occur in Tethyan ophiolites. Therefore, the spatial and temporal distributions of the Tethyan ophiolites provide clues to the evolution of the mantle from which the Indian MORB derived. The gabbronorites from the Dongcaohe ophiolite in North Qilian Mountain at NW China are characterized by ^(87)Sr/^(86)Sri ratios of 0.70282-0.70307 and initial εNd values of 4.5-5.2. They plot on the ^(87)Sr/^(86)Sr-^(143)Nd/^(144)Nd mantle array below the field for Pacific and Atlantic MORB, implying a mantle origin with trivial extents of post-magmatic alteration. The Dongcaohe gabbronorites also differ from the Pacific and Atlantic MORB for higher ^(207)Pb/^(204)Pbi (15.428- 15.431) and ^(208)Pb/^(204)Pbi (36.78-36.94) at a given ^(206)Pb/^(204)Pbi (17.12-17.22) value. These Sr, Nd, and Pb isotope characteristics are similar to that of modern Indian MORB and Paleo- and Neo-Tethyan ophiolites. It is hence concluded that the ancient oceanic mantle beneath the North Qilian Mountains belongs to the Tethyan tectonic domain and the constituent materials of the North Qilian orogenic belt were from the Gondwana continent rather than the Paleo-Asian oceanic suture system. With a formation age of 497±7 Ma, these gabbronorites represent relicts from the Proto-Tethys and indicate that the Dupal anomaly has lasted for at least 500 Ma. The 300-440 Ma Paleo-Tethyan ophiolites and the 90-200 Ma Neo-Tethyan ophiolites occur respectively on the south and southwest of the Dongcaohe ophiolite. Based on this Tethyan ophiolite distribution pattern, it is inferred that the rift zone on the northern margin of the Gondwana continent shifted from east to west during 500-100 Ma, providing an important constraint for reconstructing global tectonic evolution history.