This is a good point. I'm Bengali (but from the western part). People I have met from the eastern part (Bangladesh) identify themselves culturally as Bengali, b

This is a good point. I'm Bengali (but from the western part). People I have met from the eastern part (Bangladesh) identify themselves culturally as Bengali, but politically as Bangladeshi. So the adjective is Bangladeshi (Bangladeshi government, Bangladeshi flag, Bangladeshi Army etc etc). As an aside Bangla = the ethnicity, Desh = Country, so country of the Bengalis.