The main hate for Bengalis from bimarus stems from early days of the British raj.
As western education was thriving in calcutta, a lot of bengali upper caste gentlemen were becoming doctos, lawyers, administrators and getting posted in Hindustan.
While the hindustanis remained mostly illiterate and the educated folks like kayasthas, syed and ashraf muslims knew only the Persian script.
That's why they were not able to get the prestigious British sarkari Naukri
What these scums did in 1970s is that made sure Hindi is the only language other than English which would be the medium of civil service exams.
They could do these because they had a higher population and higher representation.
Hindi urdu controversy emerged after they lost their mughal masters.
The British said that official language of provices of agra and awadh would be english and Hindustani (written in Persian script)
Then the pandits made sure to forcefully engineer hindi as a language with a script called devangari which was used in north west to write sanskrit.
Muslims made the same Hindustani language more persian.
https://franpritchett.com/00islamlinks/txt_sir_sayyid_meerut_1888.htmlhttps://franpritchett.com/00islamlinks/txt_sir_sayyid_meerut_1888.html
