Well. I am from an NIT in India and upper caste groupism is super common there. Of course to an outsider it seems like these are guys from the same high school and same hostel hanging out, but in reality it is mostly upper caste Brahmins in those high schools as well who end up continuing their groupism and favoritism in college and beyond. The same groupism exists even today - decades later. You see the same upper caste brahmins hanging out in the US together still in their close knit groups.