Based on the analysis of the whole Tethys domain, we studied the tectonic evolu tion of the eastern Kunlun—northern margin of the Qaidam basin from the point o f volca n ic activity. It is apparent that the Early Paleozoic volcanic activities of the eastern Kunlun—northern margin of the Qaidam basin are related to the extension p rog r ess when the Qaidam microplate separated from the North China plate in the Ear l y Pa leozoic. Although there formed stretching basin or small oceanic basin in the ce ntra l Kunlun area, Qiman Tagh and the northern margin of the Qaidam basin, typical oceanic crust has never been formed. In addition, we calculated the t hickness of the l ithosphere by modeling trace elements.