Undocumented cross-border migration is an active agent of the state indeed. The inflow single-handedly affects the state policies and bilateral relations with the source country. In this process of interaction, these movements get altered reciprocally. In a heterogeneous society like South Asia, recurrent tension persists between groups and even the States. As a result, the region remains vibrant in territorial and communal disputes. South Asia witnessed a great exodus and constant illegal migration across the borders that shaped the politics in the region. The paper attempts to analyze the inconsistent attitude toward different cross-border migrations in South Asia. The analysis has contextualized the affairs of the state and the history of South Asian countries. The uncertainty of immigrants and the absence of a proper legislative framework exclusive to South Asia results in administrative ad hocism.