Polyculturalism-a conceptualization of culture that, rather than examine cultures as discrete social historical phenomena, instead focuses on the extent of their imbrication, that is, the varying ways in which people’s cultures and histories are inextricable and interwoven. It contrasts with multiculturalism, which often regards cultures as discrete, separate entities.
This theory is elaborated upon at length in Vijay Prashad’s book Everybody Was Kung Fu Fighting.
You have a good point! This is especially when discussing modern African cultures that have been contaminated by European and Asian cultures!