The north China block (NCB), part of the Sino-Korean craton, is surprisingly one of the most active seismic regions in the world. The south China block (SCB), another major craton in East Asia, has been seismically quiescent. Using the updated GPS data and finite element modeling, we show that the kinematic boundary conditions are the primary cause of the contrasting seismicity. The SCB, facilitated by large strike-slip faults on its boundaries, moves coherently as a rigid block. Conversely, sandwiched between the expanding Tibetan plateau and the stable Siberia, the NCB experiences large differential stresses, which are further enhanced by faulting and thermal thinning of the lithosphere. The spatial agreement between seismic energy release in the past ~2000 years and the predicted long-term strain energy implies that intense seismicity in the NCB may continue in the future.