Game concept
Rally Point
The game also links it as Rally Points.
From the game's encyclopedia
A Rally Point is a mustering ground for the Levies and Men-at-Arms under your command.
In times of War, you can call up your Soldiers at a Rally Point to gather an Army.
The Levies assigned to a Rally Point must come from either your own Domain or your Vassals. Rally Points can be reorganized, split and merged as you see fit.
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.
Rally Point is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Rally Point is a mustering ground for the Levies and Men-at-Arms under your command." The game also links it as Rally Points. 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.