The paper is an attempt to apply the constructive and anti-primordialist approach to the issues of ethnicity and identity - an approach introduced in anthropology as a fruitful interpretative framework since the seminal work of F. Barth (1969) - to the analysis of ethnographical data collected between 2008 and 2015 in a lower-class quarter of central Khartoum, Deim. More precisely, we focus on the labels of « Southerner » (janûbi) and « Northerner » (shimâli), and how they are conceived and performed by the inhabitants of this quarter. By embedding the identity categorizations of local inhabitants in the particular history of the quarter’s genesis, during the colonial period, and its further development, parallel to urbanization dynamics of the capital, we underline two of the main issues regarding ethnicity and other identity dynamics. First, the active process of the construction of an overarching identity as « Dayâma » taking into account the plurality of ethno-tribal cultural representations through the insistence of an underlying class dimension. Second, the shifting borders of the ambiguous dichotomy of “Southern”/”Northern” and its cultural contents, whose political value is enhanced within the wider context of identity reconfigurations after the benchmark of South Sudan’s separation in 2011.