https://forum.paradoxplaza.com/forum/developer-diary/dev-diary-172-the-full-medieval-world.1756319/
China
>Hegemony tier (higher than empire, no generic types de jure cases than Rome & India)
>Celestial Government, administrative with house heads, governors, and influence, but appointments are based off of Merit, an unspendable ranking accumulated over time by doing a good job and attending Examination activities
>Imperial Treasury: money is sent up towards the emperor, then repaid to governors in a salary, separating personal from governor treasuries, and can only be spent on things like buildings, troops, or disaster relief
>Dynastic Cycle: Stable (Expansion and Advancement), Unstable Era, Chaotic Eras
>Chinese Tributaries can receive the benefits of the Middle Kingdom
Japan
>Ritsuryō administrative governors (mostly 867 and 1066) and Soryō landed lords (mostly 1178)
>House relations are tracked, moving along scales (house feud update?), and can form Blocs, as family confederations
>Rule over Japan is a contest similar to Byzantine Emperor acclamation, as the Emperors were often relegated to ceremonial roles. Kampaku (Ritsuryō) can rule via appointment, while a Shōgun (Soryō) can lead via faction, else the Ten’nō himself can also rule as Kampaku, or "abdicate" to be a cloistered emperor
>Japanese mostly are OPM and so have manors and House Aspirations
SEA
>Mandala Government for Buddhist and Hindu States, reliant on tributaries than demesne, and authority is more reliant on Piety than prestige or sometimes gold
>Temple Citadel as Main Holding Type, with Great Projects to fund your Capital Temple
Other Features
>Great Projects: a building that can be funded by multiple characters, such as the Great Wall or a disaster relief package after a Natural Disaster
>Natural Disasters: a situation to strike areas, creating issues if not solved via Great Project
>Silk Road: not in detail, but will flow when stable, spreading innovations
Korea, north steppe, SEA tribes TBD