In history, most of the tributary status aren't concluded after a "tributary war" or something like that, but after another sort of war. It can be interesting to add a possibility to conclude a tributary relation after a war, like for the hostage option. For the one which becomes a tributary, it allows you to have a truce of unlimited time, as long as the tribute is paid, for the other party it allows you to obtain a tribute.
#Tributary as peace option
hearty sun
glass phoenix
Agree but I feel like that'd need balanced in some way, I can already see that getting way out of hand and a player or ai being able to get absurdly overpowered relatively quickly