Yes, AI plays on Chieftain level.
Find the GlobalAIDefines.xml, find the node written below, and change its value to HANDICAP_PRINCE.
Code:<PostDefines> <Row Name="AI_HANDICAP"> <Key>HANDICAP_CHIEFTAIN</Key> <Table>HandicapInfos</Table> </Row> </PostDefines>
Give it a try, I'm wondering whether the game becomes more balanced and remains challenging at the same time.
Unfortunately, the game gets ridiculously easy if you set AI_HANDICAP to prince. AI needs a lot of help to be a "challenge". Frustrating, but true.