Game concept
Tribal Holding
The game also links it as Tribe, Tribes, Tribal Holdings.
From the game's encyclopedia
Tribes are poor in Taxes but rich in Levies, Prestige, and Men-at-Arms upgrades. They have limited upgrade potential and, while strong early, quickly dwindle in power the longer time progresses. Only Tribal characters can hold them without penalties.
If a Tribe exists in a County, no other Holdings can be built. Feudal rulers will have to spend Gold to transform Tribes into Castles.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Tribal Holding is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Tribes are poor in Taxes but rich in Levies, Prestige, and Men-at-Arms upgrades." It is part of Holding Type. The game also links it as Tribe, Tribes and Tribal Holdings. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.