The phrase "mountain tribe" refers to a group of people who live in or are associated with the mountains. They have their own cultural traditions, language, and way of life that is unique to their mountainous environment. Full definition
After a tour in which mountain tribes in the north are visited, a boat trip on the Ou, via the Pac Ou caves filled with Buddha statues, to Luang Prabang. (off-the-beaten-track.net)
Played by Winston Duke (Person of Interest), M'Baku is the leader of a Wakandan mountain tribe known as the Jabari. (inverse.com)
When mountain tribe leader M'Baku (Winston Duke) challenges T'Challa for the throne, for instance, one of his biggest gripes with the way things have been going is that Wakanda's greatest assets have been entrusted to «a child.» (vox.com)