Most monarchies appear to have been elective originally, but dynasties early became customary. In primitive times, divine descent of the monarch was often claimed. Deification was general in ancient Egypt, the Middle East, and Asia, and it was also practiced during certain periods in ancient Greece and Rome. A more moderate belief arose in Christian Europe in the Middle Ages; it stated that the monarch was the appointed agent of divine will. This was symbolized by the coronation of the king by a bishop or the pope, as in the Holy Roman Empire.

Although theoretically at the apex of feudal power (see feudalism), the medieval monarchs were in fact weak and dependent upon the nobility for much of their power. During the Renaissance and after, there emerged new monarchs who broke the power of the nobility and centralized the state under their own rigid rule. Notable examples are Henry VII and Henry VIII of England and Louis XIV of France. The 16th and 17th cent. mark the height of absolute monarchy, which found its theoretical justification in the doctrine of divine right. However, even the powerful monarchs of the 17th cent. were somewhat limited by custom and constitution as well as by the delegation of powers to strong bureaucracies. Such limitations were also felt by the benevolent despots of the 18th cent.

Changes in intellectual climate, in the demands made upon government in a secular and commercially expanding society, and in the social structure, as the bourgeoisie became increasingly powerful, eventually weakened the institution of monarchy in Europe. The Glorious Revolution in England (1688) and the French Revolution (1789) were important landmarks in the decline and limitation of monarchical power. Throughout the 19th cent. royal power was increasingly reduced by constitutional provisions and parliamentary incursions.

In the 20th cent., monarchs have generally become symbols of national unity, while real power has been transferred to constitutional assemblies. Over the past 200 years democratic self-government has been established and extended to such an extent that a true functioning monarchy is a rare occurrence in both East and West. Among the few remaining are Brunei, Oman, Saudi Arabia, and Swaziland. Notable constitutional monarchies include Belgium, Denmark, Great Britain, Japan, the Netherlands, Norway, Sweden, and Thailand.