This article examines concepts of ‘home’ and ‘abroad’ for migrants and citizens in the twilight of empire. It focuses on the ‘cheminots refoulés’, railway workers with origins in the former French Sudan (today's Republic of Mali) who were expelled from Senegal shortly after both territories declared independence, and other ‘Sudanese’ settled in Senegal, sometimes for several generations. Using newly available archives in France, Mali and Senegal, and interviews with former cheminots and ‘Sudanese migrants’ on both sides of the border, this article seeks to historicize memories of autochthony and allochthony that have been constructed and contested in postcolonial nation-building projects. The Mali Federation carried the lingering memory of federalist political projects, but it proved untenable only months after the Federation's June 1960 independence from France. When member states declared independence from each other, the internal boundary between Senegal and the Sudanese Republic became an international border between Senegal and the Republic of Mali. In the wake of the collapse, politicians in Bamako and Dakar clamoured to redefine the ‘nation’ and its ‘nationals’ through selective remembering. Thousands of cheminots and ‘Sudanese migrants’ who had moved to Senegal from Sudan years (or decades) earlier were suddenly labelled ‘foreigners’ and ‘expatriates’ and faced two governments eager to see them ‘return’ to a hastily proclaimed nation state. This ‘repatriation’ allowed Republic of Mali officials to ‘perform the nation’ by (re)integrating and (re)membering the migrants in a nascent ‘homeland’. But, having circulated between Senegal and Sudan/Mali for decades, ‘Sudanese migrants’ in both states retained and invoked memories of older political communities, upsetting new national priorities. The loss of the Mali Federation raises questions about local, national and international citizenship and movement in mid-century West Africa. Examining the histories invoked to imagine postcolonial political communities, this article offers an insight into the role that memory has played in constructing and contesting the nation's central place in migration histories within Africa and beyond.