@where-is-my-bed i was going to reply in the comments section but it got too long and i wanted to share my response with everyone as well (bc i clearly can't shut up abt this LMAO)
ramy is from kolkata (calcutta in the book) which, despite still being nationally indian, is culturally bengali. even tho a lot of bengalis including kolkata bengalis happen to know urdu from various sources, bangla was and is the main language there. native urdu speakers tend to be more densely populated further away from kolkata (not to mention current day pakistan which, for anyone that doesn't know the geography, is literally on the opposite end of india).
there are 2 main reasons why ramy having urdu as one of his main languages tied to his identity is so ::bites fist::
back in the mid-19 century (after babel is set), there was this rising rhetoric of urdu being the language of indian* muslims as opposed to hindi for indian* hindus. this is furthered by the hindu-muslim conflict. as ramy is muslim, his main languages being urdu, arabic and persian directly reflect the seeds of this rhetoric. arabic and persian were already 'the languages of islam' and therefore so was urdu, compared to bangla which has strong sanskrit ties.
in the partition of bengal ā for the sake of brevity, i leave assam out of this note ā the british split bengal to east pakistan (now bangladesh) and west bengal (india, where kolkata is). when bangaldesh was east pakistan, the rhetoric from point 1 intensified to imply bangla as inferior to urdu due to the hinduism embedded in bengali culture. this led to the bengali language movement where bengalis fought for our right to speak bangla.
indian* āĀ in reference to british india specifically, so this includes current day bangladesh and pakistan
ramy's whole identity, not just as an indian muslim, but being from kolkata and yet speaking urdu, literally speaks to babel being a book about languages and racism and colonialism. ramy being forced, like robin with his cantonese, to abandon bangla for the sake of oxford and the british empire's potential exploitation of india's internal conflicts is soooo gut-wrenching when you realise all this historical context
and sure, none of this is explored to this much detail in babel because ramy isn't the main character. but it's just such an interesting choice which very much reflects on the politics of the time and beyond. i don't know, it feels like an intentional choice that i definitely believe happens off-page (and if not, then it's fanfic material)
i went into this book expecting ramy to speak bangla because for once a well-written book by a non-bengali included a bengali character, and even though he doesn't actually speak any bangla, the hints of his bangla being poor (very common experience for british bengalis) and the racism he experienced was so particular UGHH
i can only imagine how ramy would've felt like being teased for not knowing sanskrit despite his appearance, and while the most common non-bengali interpretation of this would be "lol india is so much more diverse ?? not every indian person knows sanskrit you bloody duck", in my eyes, the ignorance would've made me resent the cards i was dealt with. "i could've learnt sanskrit if i was told i should study bangla instead, but no. now i have to feel like an inferior indian AND an inferior muslim for needing to pick a side. a side i did not even want to choose" because before the violent partition, bangla and bengali culture showed us that hindus and muslims could coexist
and like babel demonstrates clearly with the opium plot line, how the british grew it in kolkata so they could drug china, and how they tore robin and ramy apart by force, the british also don't want hindus and muslims to come together. they treated us both so horribly under their rule and to make sure we didn't fight back, they made us fight each other. yes, we were already fighting each other before, but not unlike any other nation. the violence we're seeing now was amplified by the british for their gain alone