fatchance:
Ethnic group and tribe are NOT the same thing. Saying they are a tribe implies a complete political system, and ethnic group does not.
A tribe is not necessarily a unique ethnic group, although it can be.
A simple way to see the difference is that a tribe, has a chief (or equivalent). An ethnic group does not. (or at least may not) A tribe without a political structure is not a tribe.
trolls_fatter:
So do I change it or not? Are people this politically correct? Had no clue I was saying anything wrong
Actually, I don't know that you were wrong. I don't know if it is a specific tribe that is being referred to or a number of tribes making up an ethnic group. On that basis, I believe what you said was just fine.