"The story of the Chittagong Hill Tracts (CHT) is one of the most tragic episodes in recent history. Once inhabited by tribals, this beautiful land has been substantially captured by the Muslims. Between 1979 and 1984 the Government settled about 4 lakh Muslims in the CHT area. [... it] led to clashes and protracted armed resistance by the major tribal group - the Chakmas. In this explosive situation, the regime sought a military solution and thousands of refugees crossed over to India. In 1974, there were 5.08 lakh people in the CHT area. .... The threats to the ethnic identity and culture as well as their land were evident."
January 1, 1970
https://en.wikiquote.org/wiki/Illegal_immigration_to_India