- Wikimedia Commons
Jamguo: Wikimedia Commons image of Xi'an's city wall
(https://commons.wikimedia.org/wiki/File:XiAn_CityWall_DiLou.jpg)


- Paradox Forums users
LordPeter: retouched portrait background images from Wikimedia Commons image ("tribal" interior)

SirRitter: retouched military headgear assets for Georgian and Baltic portrait sets

Lysten: taoist religious clothes and late-era papal tiara


- Other CK2 mods
Lux Invicta: various headgear
(https://forum.paradoxplaza.com/forum/index.php?threads/mod-lux-invicta.612823/)

A Game of Thrones: various headgear
(https://forum.paradoxplaza.com/forum/index.php?threads/release-a-game-of-thrones-v1-0.889743/)

Horse Lords Remake + New Portraits & Units mod: headgear assets for Uyghur, Khitan, and non-pagan Mongol portrait sets
(https://steamcommunity.com/sharedfiles/filedetails/?id=485482054)

Steppe Faces mod: beard, hair, cloth, and headgear assets in the steppe area
(https://forum.paradoxplaza.com/forum/index.php?threads/mod-crackdtoothgrins-graphical-goodies.603794/)