Game concept · All Under Heaven
East Asian Mansion Building
The game also links it as East Asian Mansion Buildings.
From the game's encyclopedia
East Asian Mansion Buildings are unique and persistent improvements to a East Asian Mansion.
A large variety of structures are available for construction and may be built by the Mansion's owner to generate private income, expand the family's Influence, and gain access to a number of Decisions, Interactions, and more.
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.
East Asian Mansion Building is an entry of Crusader Kings III's in-game encyclopedia (All Under Heaven). The game explains it: "East Asian Mansion Buildings are unique and persistent improvements to a East Asian Mansion." It is part of Domicile Building. The game also links it as East Asian Mansion Buildings. Patch 1.20.1.2, from game/common/game_concepts/tgp_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/tgp_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.