Relationships between vassals and stronger states have been around since the early development of state relations.

The stronger state typically agrees to provide military support and any other existential support to keep the vassal state afloat in times of crisis. In return, the dominant state receives commercial, military or tributary (taxes) privileges.

Vassal states typically agree to the deal out of a combination of consent and/or implicit force. Vassal states benefit from a greater degree of autonomy then annexed territories, provinces or colonies, although decisions of high strategic value are controlled by the foreign power.

This dependency can compromise the sovereignty of vassal states to the point of total loss of freedom, if the relationship of dependency is allowed to degenerate into one of subjugation, which can often happen when empires disintegrate violently.

Empires have commonly used vassal states to expand their spheres of influence. It helps them secure their key strategic interests without having to incur the costs of direct administrative control of a region.

During the reign of Thutmose III (1479 BC – 1425 BC), the first recorded vassal states in history emerged, with Egypt winning the loyalty of the city-state kingdom of Byblos and other small states in northwestern Syria.

Due to these vassal states’ distance from the Nile, and their value as buffer zones from the Hittites in Anatolia, or the Assyrians to the East, these states enjoyed a more high-status relationship with Egypt then other surrounding regions. They could solicit the Pharaoh for various requests in exchange for favored commercial ties, and for allowing their land to be used as bases for military activity.

In the current world order, empires and vassal states have been replaced by dominant powers exercising the same types of influences with client states. While the form of these relationships has evolved, the essence remains the same.

Today’s vassal states are either informal ones, called “client states”, “puppet states”, “satellite states” or more formal de jure types, such as “protectorates”.