A list has been published in India which effectively strips around four million people of citizenship in the north-eastern state of Assam.
Authorities believe illegal Bangladeshi migrants are living in the area amongst already established Bengali Muslim communities.
India has ordered all 32 million residents to prove they came to the state by 24 March 1971, a day before Bangladesh declared independence.
To avoid violence, officials say that no-one will face immediate deportation though there are fears the move could spark a witch hunt of the region’s ethnic minorities.