Are the Vietnamese and Chinese languages related? Or perhaps one of the two cultures was introduced to that fruit by the other, and thus preserved the name?
Not related at all in recent history and I have no insight on the etymology links but Vietnamese used to be written in a mix of original Vietnamese Chinese-style characters before they changed to a Latin alphabet with Colonialism and Communism so there was definitely contact.
Thank you
China ruled Vietnam for a thousand years (111 BC–939 AD) so I'm sure there was some linguistic cross pollination.
Though tomatoes come around long after that period...