Game concept
Nomadic
The game also links it as Nomadic Government, Nomads, Nomad.
From the game's encyclopedia
Nomadic Rulers graze County Fertility to grow their Herd. They can use Herd as Nomadic Horde, which can be upgraded to Men-at-Arms. They have a Nomadic Capital.
Nomads can Migrate to find more fertile lands, though large nomadic Realms can grow their herd through Tributaries or by reaching a high Fertility Equilibrium.
Nomads have a higher maximum Dread.
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.
Nomadic is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Nomadic Rulers graze County Fertility to grow their Herd." It is part of Government. The game also links it as Nomadic Government, Nomads and Nomad. Patch 1.20.1.2, from game/common/game_concepts/mpo_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/mpo_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.