A dramatic increase in physical mobility is a hallmark of the transition to modernity in any society. The combination of economic industrialization, mechanization of transportation and proletarianization of labor makes migration necessary for effective development. This paper will examine concepts of modernity to elucidate the central role played by migration in transition to economic, social, cultural, and political modernity. Changes in internal and external migration in 19th and 20th century China, Japan, and Korea will be examined along with conventional historiographical periodization to see how understanding modernity as movement can and should alter our understanding of East Asian history.