The relationship between secularism and religious politics in South Asia has deep historical roots, shaped by centuries of religious interactions, colonial rule, and postcolonial state-building. This chapter examines the evolution of secularism and religious politics in the region by tracing their historical foundations from the pre-colonial era through British colonial rule to the immediate aftermath of the Partition of India in 1947. By exploring the religious dynamics of the pre-colonial period, the colonial administration’s role in institutionalising religious divisions, and the impact of these developments on modern nation-states, this chapter provides a comprehensive understanding of how secularism and religious politics have evolved in South Asia.