"The influx in cetain cases, has changed the demographic character .... Its serious religious and cultural dimensions are being increasingly felt in the states of West Bengal, Tripura and Bihar.... The simmering communal tension in some of the border areas is one of the manifestations of the effects of large scale illegal migration of Bangladeshi nationals who have slowly displaced or dispossessed the local population, particularly those belonging to the Hindu community, in these areas."
January 1, 1970
https://en.wikiquote.org/wiki/Illegal_immigration_to_India