Vassal states
Vassal states are an important feature of pre-modern civilisation and should be modelled.
Also called: client state, satellite state, associated state, puppet state, neo-colony, protectorate or tributary state.
The controlling state is called a suzerain, surrogate or hegemon.
List of dominant sovereign states and their servient territories
The Process
The more powerful civilization demands that the less powerful civilization accepts its suzerainty. As part of the demand, a tribute is set.
The less powerful civilization accepts as becomes the vassal, whilst the more powerful civilization becomes the suzerain.
Does the vassal retain diplomatic relations with other civilizations? ?
Does the vassal control its military units? Yes
Does the vassal control domestic expenditure (e.g. military/research/infrastructure)? Yes
Perhaps model via alliance and relationship score.