In line with the democratic principles of ancient Athens, this function was performed by citizens on a project basis and took the form of emissaries visiting a neighbouring city or state, rather than any permanent delegation or secondment.
Emissaries were known as either "kerykes" or "presbeis". Kerykes simply delivered messages from the assembly and had no negotiating power. Their usual role entailed the proposing of an agenda for a subsequent visit by a presbeis.
The presbeis were older and wiser citizens, usually well respected and connected, who held the power to negotiate, albeit always within limits pre-set by the Assembly.