This article examines the history of South Asian immigration to Argentina before the First World War. The arrival of a relatively small group of Sikh laborers in 1912, alongside other Japanese and Chinese immigrants in the preceding decade, sparked a huge reaction from Argentine politicians and immigration bureaucrats. They restricted entry, pushed for labor market exclusion, and engaged in diplomatic exchanges with British imperial authorities. In their view, mass migration not only had the power to make a white, European nation but also threatened to undermine that same project. This article argues that the dominant vision of Argentina as a white nation was built on not only transatlantic immigration but also Asian exclusion. Drawing on archival research in Buenos Aires and London, it casts new light on both Argentine nationalism and the language of racial hierarchies mobilized in discussions of immigration.