Vassal state

A vassal state is any state that has a mutual obligation to a superior state or empire, in a status similar to that of a vassal in the feudal system in medieval Europe. Vassal states were common among the empires of the Near East, dating back to the era of the Egyptian, Hittite, and Mitanni conflict, as well as in ancient China.

The relationships between vassal rulers and empires were dependent on the policies and agreements of each empire. While the payment of tribute and military service was common amongst vassal states, the degree of independence and benefits given to vassal states varied. Today, more common terms are puppet state, protectorate, client state, associated state, or satellite state.