How does YOUR Civ become anothers Vassel?

[AriochIV]

Given that Khan had to re-ask for the resources every turn, I think something was not quite right there.

 

[Lord Parkin]

My guess is that it's probably just buggy for the AI... I would sincerely hope that resource gifting (etc) does indeed work properly for human players.

By the way, I'm also sad that humans can't become vassals of the AI, though I can sort of understand why. I'm glad though that it's still available between humans in multiplayer.