India is an extremely genetically diverse nation, with considerable cultural, religious and linguistic diversity. So, what are the common features of India? English, common law and parliamentary democracy: all legacies of British rule.
Pakistan is a nation with considerable cultural and linguistic diversity. So, what are the common features of Pakistan? Islam, English, common law (being nibbled away by Sharia) and (on a it-comes-and-goes basis) parliamentary democracy. The Middle Eastern Islam (pdf) of Pakistan is eating away at its other institutional commonalities.
Bangladesh ('the country of Bengal') is a country with very little cultural or linguistic diversity. For it, Islam, English, common law and parliamentary democracy are part of a dominant ethno-nationalist identity. It seems to be doing somewhat better than Pakistan, but not as well as India, suggesting that the ethno-nationalist identity is somewhat ameliorating the negative effects of Islam.
