@EmmaMusic
I love the intricate and in-depth detailing of this question. Gosh! I’m admiring the amount of effort that you’ve put in.
Coming to the question:
Since the 2 archaeologists have been taken hostage, we are left with the Historian, the Phycisian and the Geologist. Now the tribesmen are looking for friendship, sincerity, emotion, courage and honesty. So now how do we convince them?
Now the historian would ideally be knowing about the history of the Tribes. So we can assume that he knows there touch points. He can help the tribe with strategic planning to get an advantage over their enemies, if any, along with various other secret passages or places that the tribe might not be aware of or wouldn’t know how to use such secrets.
The Physician would help the villagers in coping up with different diseases or educating them about various medicinal requirements keeping in mind the dangers of their surroundings.
The Geologist could help the tribe by teaching them agricultural techniques (a bit wide-off mark thing to say) as per the demographics of their land.
Now, once the courage is shown to stand for their friends to get them out of prison, and help is done leading to a development of mutual respect, the 3 wise men can then tell them of their journey and share tales so as to make the tribe know the purpose of their visit and the importance of the two Archaeologists to the world and to the group. They would make the tribe understand that their tribe and their territory is a part of the world and that world cares about them. Once, the motive of ‘no harm intended’ is apparent to the tribe, the crew should be good to return back to where they came from with a promise to ‘visit the place again’.