Among India’s neighbouring countries, Bangladesh occupies a unique geographical location. It shares a land border, India’s longest, with four Indian states—Assam, Meghalaya, Tripura and West Bengal. While all neighbours share civilisational ties with India, Bangladesh shares a unique and abiding link and a foundational principle of its nationalism—Bengali language and culture—with West Bengal mainly, but also to some extent with the Bengali-speaking migrants who settled in Assam. Muslim migrants also share a religious affinity.