A kingdom is a piece of land that is ruled by a king or a queen. A kingdom is often called a monarchy, which means that one person, usually inheriting their position by birth or marriage, is the leader, or head of state.

Kingdoms are one of the earliest types of societies on Earth, dating back thousands of years. There have been hundreds, if not thousands, of different kingdoms throughout history. Kingdoms can be huge, such as the United Kingdom. During the 19th century, the United Kingdom, ruled from London, England, stretched over five continents. Kingdoms can also be small, such as the kingdom of Brunei, which is smaller than the U.S. state of Delaware.

Kingdoms are rarely ruled by an absolute monarch, a single king or queen who makes all decisions for the entire state. Kingdoms are usually broken into smaller territories, such as city-states or provinces, that are governed by officials who report to the monarch. Most modern kings and queens do not control the government. Elected leaders and constitutions establish laws for most kingdoms today.

Early Kingdoms

The world’s earliest kingdoms developed thousands of years ago when leaders began conquering and controlling cities and settlements. Rulers of early kingdoms provided protection to their residents, or subjects. In return, subjects paid taxes or services to the monarch. Kingdoms also had the power to create and enforce laws.

The first kingdoms were established about 3000 B.C.E. in Kengir, also known as Sumer, and Kemet, also known as ancient Egypt. Sumer was a kingdom that existed between the Tigris and Euphrates Rivers in what-is-now Iraq. The Sumerians had their own written language and undertook complicated construction projects, such as irrigation canals and large temples called ziggurats. There is also evidence that the Sumerian kingdom traded and fought with neighboring peoples.

A few thousand years later, the kingdom of Teotihuacan developed in North America. The kingdom was centered in the city of Teotihuacan in modern Mexico City, Mexico. Teotihuacan probably had more than 100,000 inhabitants, making it among the largest ancient kingdoms in the world at that time.

Many, but not all, ancient kingdoms were empires. Empires are geographically large political units made of many different cultural or ethnic groups. Empires were often headed by monarchs, making them kingdoms. Kemet was a kingdom ruled by a monarch called a pharaoh, for instance. The Kemetan empire reached its height in the so-called “New Kingdom” period, under the leadership of the pharaoh Amenhotep III (1390-1352 BCE). Kemet in the New Kingdom stretched from modern-day Egypt, along the Mediterranean coast to modern-day Turkey in the north, and modern-day Eritrea in the south.

Many empires did not have monarchs, however, so empire and kingdom are not always the same thing.

Medieval Kingdoms

The Middle Ages was a period in history that lasted roughly from about 500 to 1500. It is also referred to as the medieval period. During the Middle Ages, countless kingdoms formed and collapsed throughout Europe, Asia, and Africa.

In Europe, many small kingdoms were formed and fought over by tribes following the collapse of the Roman Empire in 476. Tribes such as the Ostrogoths, from modern Romania, and the Franks, from modern Germany, were among those that formed small, unstable kingdoms in the early Middle Ages.

Perhaps the most famous European kingdom of the Middle Ages was that of Britain’s legendary King Arthur. Arthur may not have existed at all. Accounts of his kingdom were written hundreds of years after it supposedly existed. If there was a King Arthur, he probably lived during the fifth century, after the Romans left Britain and before the emergence of actual, historical British kings in the eighth century. King Arthur would have been one of dozens, or perhaps hundreds, of kings in Britain at the time. Even if King Arthur did not exist, his legend suggests kingdoms played a role in the Middle Ages.

At around the same time tribes and small kingdoms were warring over parts of Europe, the African kingdoms of Ghana and Mali were among the strongest of the Middle Ages. The Ghana Empire, also known as the Wagadou Empire, formed about 790. It found success as a major trading center. The Ghana Empire, located in the modern countries of Mauritania and Mali, was a kingdom on the southwest edge of the Sahara Desert. Caravans with hundreds of camels would travel across the Sahara like ships crossing a sandy sea.

The kingdom emerged as a trading center for gold and salt. (Salt, a valuable preservative for food, was nearly as valuable as gold.) The trade of ideas also flourished in the kingdom, as the religion of Islam spread westward from the Arabian Peninsula to the western coast of Africa. The Ghana Empire was weakened and eventually collapsed because of rapid growth, drought, and weakened trade.

About 1200, the Mali Empire rose out of what was once Ghana. Mali became a strong kingdom under the leadership of King Sundiata. Sundiata’s kingdom stretched from the Atlantic coast of the modern countries of Senegal and Mauritania to the inland area of southeast Mali. Like Ghana, the Mali Empire depended on trade routes through the Sahara. Unlike Ghana, this kingdom actually had its own gold mines within its borders. One of the kingdom’s major cities was the trade hub of Timbuktu, in the modern nation of Mali. Timbuktu was the major trade city on the edge of the Sahara for hundreds of years, trading gold, ivory, salt, and enslaved people.

Later Kingdoms

After many centuries of war and turmoil, stronger and more sophisticated kingdoms began to develop throughout the world. In Europe, the kingdoms of Portugal, France, and England expanded across vast territories after the discovery of the Americas in the late 15th century.

Kingdoms established stronger diplomatic ties with neighboring governments to reduce conflict. They relied on treaties and, often, marriages to create strong alliances. Many monarchs of Europe during this period were related to each other. The British Queen Victoria had many grandchildren who were married to people across Europe, a fact that may have contributed to mostly peaceful times during her reign.

Kingdoms of this period increased trade with distant kingdoms and built strong fleets for overseas exploration. The Portuguese Empire, for instance, established ties with the Kingdom of Siam, in the modern country of Thailand. Portugal’s fleet was able to travel around the continent of Africa and along the coast of Asia to reach Siam. Portugal, which dominated trade routes in the Indian Ocean, traded for valuable spices.

The Kingdom of Siam was exposed to European technology and politics. While some Asian kingdoms, such as Japan, rejected the influence of European powers, Siam used European ideas to modernize the country. Siam reached its peak under King Mongkut, who ruled from 1851–1868. King Mongkut helped establish the first newspaper in the kingdom. King Mongkut also introduced the idea of free trade. Subjects in the kingdom could manufacture their own trade goods, such as rice or tea, for trade with foreign businesses.

Modern Kingdoms

A few kingdoms are still ruled absolutely by a monarch. King Salman bin Abdulaziz Al Saud of Saudi Arabia, King Mswati III of Eswatini, and King Hassanal Bolkiah of Brunei are absolute monarchs. All of these kingdoms have legislatures and sets of laws. The monarch remains the final authority.

However, most of the kingdoms that exist today are constitutional monarchies. The king or queen acts as a ceremonial head of state, with public responsibilities such as promoting tourism and interest in the nation’s history and culture but no real political authority. Under a constitutional monarchy, the nation is governed by a constitution, or set of laws, executed by a president or prime minister elected by the country’s citizens. In England, for example, Queen Elizabeth II is the official head of state—but the nation is governed by a prime minister and parliament.

The Kingdom of Thailand, formerly the Kingdom of Siam, is an example of a modern kingdom. The kingdom ended its absolute monarchy in 1932, and today it is a democracy with elected leaders and courts of law. However, the king of Thailand, Maha Vajiralongkorn, has reigned since 2016 after the death of his father Bhumibol Adulyadej, who was the longest-serving king in Thai history. King Adulyadej had tremendous public support and had been known to intervene in politics. His son seems to be less popular and his role somewhat uncertain.

Other modern kingdoms ruled by a constitutional monarchy include Sweden, Belgium, Japan, and Morocco.