https://forum.paradoxplaza.com/forum/developer-diary/dev-diary-176-southeast-asia.1802991/
Southeast Asia
Previous Dev Diary: >>2069362 (Japan and Korea)

Two main governments, Mandala and Wanua
Mandala Government
>has 3 extra levels of Devotion, going up to Godlike
>requires your predecessor to reach the prior level, unlocking your next tier
>Temple Citadel holding - main for Mandala, but can be held by most others in conquest
>Four Mandala Aspects, affecting levels of Devotion
>Mandala Radiance, after first tier Temple Complex, shows how far you can obtain tributes
>Three Decree Laws: Prosperity, Expansion, or Reverence
>less demesne/vassal limit, but many tributes
>can coerce tributary scheme, even stealing them away from other Mandala

Wanua
>tribal type; must reform religion/change government to advance innovations/development
>can traverse the sea and raid
>still trying to make unique

Great Projects
>required and optional contributions
>can request contributions via hooks, bribes, or piety
>China has a lot, such as the Great Wall or Grand Canals
>can spawn in response to Natural Disasters, prompting action from above and below

Tribute Missions
>for both Mandala and Hegemonic tributaries
>it's just like vassal "Pay Tribute" from Royal Court, but you can offer eunuchs, concubines, and herd, if nomadic

Celestial Tributes
>China's unique tributes, who reward the Emperor directly, more than his Treasury
>minimum expectations scale upon Imperial Grace, such as how often to pay tribute and how much
>Grace decay affected by Imperial Cycle, and can be spent to adjust contract obligations, or receive a Seal of Investiture from the Emperor (a regalia type artifact) - Trade Access (money and development), Family Access (can marry into), or Palace Access (become active in the Dynastic Cycle)
>benefits lost if the Hegemony is dissolved

Map Reviews -- the last Dev Diary before Summer Break; will return in August [for the Coronations DLC]