Tribal is the adjective from tribe. In its plain sense it just describes things belonging to a tribe: tribal land, tribal leaders, tribal languages, tribal art. In news writing you meet 'tribal conflict' or 'tribal areas'.

But you should know that this word sits on uncomfortable ground. For a long time Europeans used 'tribe' for other people's societies while calling their own 'nations', and many people now feel the word makes a group sound primitive. In Taiwan, when talking about 原住民 in English, safer and more respectful choices are Indigenous peoples, Indigenous communities, or the specific name — Amis, Atayal, Paiwan. In the United States and Canada, though, 'tribal' is the official legal word — tribal government, tribal council — and Native nations use it about themselves, so it is correct there. So the same word can be neutral, offensive, or legally exact depending on where you are.

There is also a very common modern meaning that has nothing to do with real tribes: tribal means people sticking to their own group and refusing to listen to the other side. 'Politics has become tribal' means people vote for their team, not for the argument. This use is everywhere in newspapers now, and it is always a criticism.

And in design, 'tribal' describes a style of bold black pattern — tribal tattoo, tribal print — which is a fashion label, not an accurate word about any real people.