This is the 9273rd most frequent Polish word.
tribe
A social group consisting of families or communities sharing a common ancestry, culture, and leadership.
The word 'plemionach' (tribes) here is used to refer to community groups that existed historically.
Przeczytałem książkę o starożytnych plemionach Ameryki.
I read a book about the ancient tribes of America.
The word 'plemienia' (tribe) here indicates a present-day community group with cultural ties.
Uczestniczyliśmy w ceremonii lokalnego plemienia.
We participated in the ceremony of the local tribe.
The word 'plemieniu' (tribe) is used metaphorically to signify a close-knit group of people with common interests.