By the end of the nineteenth century, terms like "white slavery", "la traite des blanches" and "Mädchenhandel" had become linguistic equivalents to describe the (coerced) transnational migration of women and their subsequent sale of sex. This book explores the historical roots of this Eurocentric conceptualization, which since its development has fed into contemporary twenty-first-century understandings of "human trafficking, especially in women and children". In unpacking these origins, the books explores how populist narratives became entangled with state and organisational practices of categorising subalterns on the move. Contributing to the historiography, "white slavery" is shown to have been not only a component of a shifting legal dogma on mobility control and international police cooperation but also a political concern of women's rights and moral reformist movements. Contrary to the sensationalized claims of the times, "white slavery" was not a phenomenon reflecting such exaggerations but rather was part of the historical development of state mechanisms to define the voluntary and coerced migration based on race and gender-based desirability.