This book examines how two of the world's most populous countries interacted between 1945 and 1967, when the concept of citizenship was contested, political loyalty was in question, identity was fluid, and the boundaries of political mobilization were blurred. The book asks probing questions of this important period in the histories of the People's Republic of China and Indonesia. What was it like to be a youth in search of an ancestral homeland that one had never set foot in, or an economic refugee whose expertise in private business became undesirable in one's new home in the socialist state? What ideological beliefs or practical calculations motivated individuals to commit to one particular nationality while forsaking another? As the book demonstrates, the answers to such questions about “ordinary” migrants are crucial to a deeper understanding of diplomatic relations between the two countries. The book argues that migration and the political activism of the ethnic Chinese in Indonesia were important historical forces in the making of governmental relations between Beijing and Jakarta after World War II. It highlights the agency and autonomy of individuals whose life experiences were shaped by but also helped shape the trajectory of bilateral diplomacy. These ethnic Chinese migrants and settlers were, the book contends, not passively acted upon but actively responding to the developing events of the Cold War. The book bridges the fields of diplomatic history and migration studies by reconstructing the Cold War in Asia as social processes from the ground up.