“What do you think of having perhaps a D'ni visitor in the history of this people...etcâ€
If you've read the D'ni histories, then you have a background history there to draw from. Having a history in hand rather than making it up is a help. But there are at least a couple of problems in your case: 1) We are forbidden to trespass upon the Cyan D'ni copyrights; and 2) What does the D'ni explorer have to do with your age: (a) How does he affect it; (b) How does his existence explain the history of that people; etc.
As you are putting it, your tribal people still require a history independent of D'ni history, so to me, the D'ni involvement seems irrelevant. And even if you can profit from some D'ni intervention, it still cannot account for what those people were from their creation down to the time of intervention.
For instance, i took the people of MotherCity out of the D'ni loop by not specifying that they had anything to do with the D'ni. MotherCity people simply speak of the Old Ones, with whom they have lost contact. However, if it becomes necessary, those Old Ones could always be D'ni. I even have posited a series of gods, one of which could always be Yehvo (i think that is his D'ni name), although i have not needed to spell this out yet.
But like your situation, this does not account for the history of this people, the ones of MotherCity. For them i have a fairly detailed description down. It sits behind everything they do and influences their actions from time to time. I am hoping this shows up in the believability of the characters. But I don't know.
If you want to see how a small part of that history is spelled out, you can read:
CREATION STORY
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Scroll down to, “The Creation Story of .....â€
also:
[ooc] PROPOSALS
viewtopic.php?f=57&t=1183
See this Creation Story Outline and Proposals for a tribal type mentality which has become fairly sophisticated in the form of the people of MotherCity.
There is behind this outline a fairly well thought out description of tribal culture as it (first) becomes Westernized; then (second) Europeanized; then (third) becomes revealed as the culture of the Modern World – a final cultural phenomenon which dates from 1700AD to the present.