In central Asia, there exists a notable NE trending boundary(Tianshan-Baikal boundary) along the western end of the Tianshan Mountains, northwestern end of the Altai Mountains and the Baikal area. On either side of this boundary, the features of topography, tectonics, seismicity and other geophysical fields are quite different. There is no major fault aligned with this boundary, while a series of NW striking faults intersect it at nearly right angles, of which the northwestern sections terminate nearby the Tianshan-Baikal boundary. Overall, the stable Kazakh platform and Siberia platform are situated in the northwestern side of this boundary, and tectonically active Tianshan, Altai and western Mongolia characterize its southeastern side. Therefore this Tianshan-Baikal boundary marks the termination of crustal deformation within the continent.