Why is India tough on infiltration, demographic change in eastern states?

It started as a humanitarian crisis, first during the Partition of India in 1947, and then the Bangladesh Liberation War of 1971. The refugee crisis transformed into an influx of illegal migrants. Gradually, it evolved into a larger discussion about demographic change, border security, identity, and governance. For decades, the issue of infiltration from Bangladesh has remained one of the most debated and politically sensitive subjects in eastern India. From West Bengal and Assam to Tripura, the impact of cross-border infiltration has shaped politics, altered population patterns, triggered social tensions, and influenced government policies. Understanding this issue requires looking beyond contemporary politics and examining the historical events, demographic trends, security concerns, and policy decisions that have shaped eastern India over the last seven decades.