In Civ6, what can you demand from a weaker civilization? In my current game I captured all but one of an opponent's cities and made peace with him. Later I needed some gold, so I tried to just demand it from him in the "Make Demand" screen, thinking I should easily get it since I can wipe him out at any time.
However, while the civ has 147 gold to trade in the "Make Deal" screen, when I go to the "Make Demand" screen it says "No available items to demand."
So, is gold off the table for demands? What can you demand?