Pinli (Diplomatic Etiquette and Protocol)
Pinli, meaning diplomatic etiquette and protocol for the visits by the lords to the king and by one lord to another, is an important part of political activity in ancient China. Depending on such factors as the status of visitor and host and the purpose and frequency of the visits, diplomatic etiquette was conducted at three levels: between two ducal lords ruling different states, involving a ministerial-level envoy, and involving senior officials. As the political conditions changed, pinli later also referred to the diplomatic ceremonial for visits involving rulers of countries and other independent political entities. The rules observed when paying tribute to a king and at other visits indicated the status and mutual relationships of the different political entities that were represented by the participants on such occasions. Later on pinli came to mean the formalities performed by the man’s side when getting engaged to a woman.
As for the relations between the ducal states, visits by officials should be exchanged annually, ministerial-level missions sent at longer intervals, and the ducal lords themselves are to pay visits on the occasion of the succession of a new ruler. (The Rites of Zhou)
According to diplomatic protocol, a superior duke has seven attendants for a given visit; a marquis or earl has five; and a viscount or baron has three. In this way their ranks are made apparent. (The Book of Rites)