EI Quintana Roo territory in south-eastern Mexico, on the border with Bel ice, was born in 1902. One of the recurrent difficulties of the territory was the lack of population and the measures taken to attract new inhabitants. And also to define these inhabitants. In this peripheral region, the population is a strategic challenge for the consolidation of national sovereignty; it expresses the assertion of a biopower — and its limits — which leads to the imposition of the racial and national characteristics of the population. By studying the radicalisation of migration policies, as well as the integration and development policies of the region (scientific expeditions, access to land, type of territorial exploitation), the aim is to introduce a different altericity from indigenous people in the discussions on the nation, mestivities and race, starting from the case of black foreigners. This research brings Mexico into the history of Caribbean post-slave societies marked by migration of Afro-descendant workers, and reports the emergence of a new political and administrative entity outside the nation. This book provides a new insight into the rationale for inclusion and exclusion in post-revolutionary mestivities in Mexico, through a double analytical gap: studying the place of black populations rather than indigenous populations; focus on immigration rather than self-employment.