Don't forget that both Veran, Onox and Aghanim bear the Gerudo Symbol.
I don't think that, the Dark Tribe are Twili, because the Twili seemed paler, with nuances of black skin.
They are more likely to be related to the Zuna(the Tribe that lived in the Desert of Doubt, and was aware of the...
You can say for sure that ALttP is on the AT,imo it is NOT!
Anyways, not much is known about the Dark Tribe... I also noticed that you didn't mention the Zunas from FSA, wich also mention a dark tribe and are very similar to Aghanim in both clothing and skin color.
They also say that the...