It still boggles my mind that so many of the languages of India are related to European languages. Hindi and English share a common linguistic ancestor. Yet languages that are much physically closer together like English and Finnish or Hindi and Tamil aren't related at all.
This is because both Europe and India where both conquered by the Yamnaya people about 4 millennia ago[1]. Europeans and Indians are (distant) cousins. Take a look at most Bollywood stars for example and the resemblance is clear.
True, it boggles my mind also! But for reasons I'm struggling to explain, it doesn't strike me as weird or surprising that, for example, American English and Navajo are completely unrelated despite being spoken in close physical proximity to each other.
I guess it is because the settlement and colonization of the Southwestern US is in much more recent memory, whereas we sort of think of Hindi and its ancestors like Sanskrit as having been spoken in India since time immemorial.
FWIW, it should be pointed out, to be strictly correct, that we really have no idea whether the various language families are related to each other and descended from some "proto-World" language. So instead of saying "X and Y are completely unrelated", it's probably more accurate to say "there is no known evidence that X and Y are related".
