Scholars have depicted the Arabization and Islamization of Sudan either as two parallel, centuries-long processes or as a set of interrelated state policies in the postcolonial era. This article contributes new chronological and empirical insights into the growing conflation of Arabic, Arabness and Islam in twentieth-century Sudan. First, it locates state efforts at Arabizing and Islamizing the South one decade before independence (1956) within the context of British imperial retreat and Northern Sudanese empowerment. Second, it examines how language and religion were increasingly enmeshed in cultural representations and school practices, even if the two were strategically distinguished in political discourses. The article assesses Southern Sudanese experience of forceful Arabization and Islamization, suggesting that cultural definitions of the nation and the access to educational, political and economic resources remain at the heart of the current citizenship crisis in Sudan and South Sudan.