I study the mechanics of regional growth through the lens of China's Down to the Countryside Movement. China compulsorily relocated millions of educated youth from urban to rural areas during the late 1960s and 1970s. About two million sent-down youth permanently settled in those rural areas. I find that an exogenous increase in the high-skilled population resulted in faster regional population and productivity growth in regions that experienced a positive human capital shock. On the other hand, in regions that experienced a negative human capital shock, an exogenous decrease in the high-skilled population resulted in slower regional population growth, but surprisingly, faster productivity growth, a phenomenon which can be explained by the increased concentration of physical capital investments in large urban areas. This last result highlights the importance of the complementarity between human and physical capital in sustaining long-term regional growth. I provide evidence that the growth effects worked through the arrival of more migrants, an increase in educational attainment, and shifts in the employment structure towards skill-intensive sectors.