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In order to better constrain the evolution of the Xing’an-Mongolia Orogenic Belt and the resulting closure of the Paleo-Asian Ocean, we conducted an integrated investigation involving U-Pb dating of igneous and detrital zircon and a synthesis of existing work across the Erdaojing and Ondor Sum complexes in the eastern segment of the Central Asian Orogenic Belt. Geochronological analysis revealed a different tectonic setting between the Ondor Sum complex (Tulinkai area) and the Erdaojing accretion complex, as detrital zircon U-Pb analysis identified different major age provenances: (1) the Precambrian basement of the North China Craton and Paleozoic Bainaimiao Arc along the northern margin of North China to the south are the provenance rocks of the schists in the Tulinkai area, and (2) the Precambrian basement of the Xilinhot complex and Paleozoic Baolidao arc to the north are the provenance rocks of the schists in the Erdaojing area. We infer that the existence of the ocean between the above two regions in the late of Early Paleozoic in accordance with the result of this study. Furthermore, a comparison of the youngest age population in the intruded-diorite rock and metasedimentary rocks with U-Pb ages implies that the final closure of the Paleo- Asian Ocean along the Solonker Suture Zone most likely occurred in the period between 239 and 222 Ma (Late Paleozoic-Triassic). © 2017, Springer-Verlag Berlin Heidelberg.