The presence of tens of thousands of Italian citizens in colonial Tunisia,unlike the history of other Italian emigrations, is not part of Italy's official memory. Nonetheless, for many decades the vicissitudes of the Italian-Tunisian communities remained at the canter of bitter international clashes and complex cultural encounters involving the opposite shores of the Mediterranean. Starting from the case study of the Italian-Tunisian communities, the thesis shed light on the interaction between the forces involved by modern migration dynamics. Drawing from the apparent irreconcilability between migrants' mixed alliances and the enduring presence of feelings, even radical ones, of national belonging, the research problematizes the transnational approach in migration studies and migration history. Indeed, while the study of Italian-Tunisian communities reveals a long history of cross-cultural encounters, of mixite and creole languages, it nonetheless remains a political history strongly characterized by the central role of state apparatuses and their bureaucracies. The history of Italian-Tunisian communities during the 20th century therefore, offers a gateway to observe the coexistence of seemingly contradictory phenomena: nationalist fanaticism and multicultural tolerance, militancy and disenchantment, racism and pluralism. To deepen the understanding of this complexity of coexisting plans, the present research focuses on the history of political allegiances in the Italian-Tunisian communities to highlight the ambiguities, the inconsistencies and the cognitive dissonance that naturally come with the situation of those who live socio- political borderlands. The concept of allegiance is central to this narrative for it allows, better than that of identity, to express the changing, incoherent, and negotiating nature of the affiliations of Italian-Tunisian migrants. To explore a story encompassing elements as imperial foreign policy, colonialism, nation building from one side and the relationship that a single migrant has with his or her village of origin from the other the present research makes use of both archival research methodologies and oral history methods. The thesis draws from archival documents of different nature, from those of the Italian and French state apparatuses, to the small association and provincial archives of colonial Tunisia up to private family archives. The interviews collected are in their turn of two types: from one side the ones recorded through the decades by journalists, scholars and archivists; on the other direct testimonies collected by the author during his fieldwork.