Merriam-Webster defines colonialism as “control by one power over a dependent area or people.” It occurs when one nation takes control of another for benefits such as resources. Often, they force their language and culture on the locals.

By 1914, Europeans had colonized a large majority of the world’s nations at some point. Japan, Korea, and Thailand are the only other nations Europeans never colonized.

Colonialism is closely related to imperialism. Imperialism is the policy or ethos of using power and influence to control another nation or people. Settler colonialism is defined as a system that seeks to replace Indigenous populations with that of the colonizing power.

Scholars can trace colonialism to antiquity, when it was practiced by empires, including Ancient Greece, Ancient Rome, Ancient Egypt, and Phoenicia. These civilizations expanded their borders into nearby areas starting around 1550 B.C. They set up colonies that used the resources and people they conquered to gain more political power.

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In Ancient Greece, for example, city-states often established colonies for extra living space and economic gain. After consulting an oracle, members of the city-state would send a group to establish a new colony.

To seal the association between the colony and the city, the founders took part in rituals, including lighting a fire from the original city’s central hearth.

During what is now known as the Age of Discovery, founding a new colony depended on another ritual. This usually meant getting support from a rich patron, often a king or queen. Then, explorers would set sail on large ships to look for unceded land.

Beginning in the 15th century, Portugal began looking for new trade routes and civilizations outside Europe. In 1415, Portuguese explorers conquered Ceuta, a coastal town in North Africa, kicking off an empire that would last until 1999.

Soon the Portuguese had conquered and populated islands like Madeira and Cape Verde. Portugal’s rival nation, Spain, decided to try exploration too.

In 1492, Christopher Columbus began looking for a western route to India and China. Instead, he landed in the Bahamas, kicking off the Spanish Empire. Spain and Portugal soon became locked in competition for new territories and took over Indigenous lands in the Americas, India, Africa, and Asia.

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The rest of Western Europe swiftly followed. England, the Netherlands, France, and Germany began their own empire building overseas. They fought Spain and Portugal for the right to lands they had already colonized.

Often, small groups of European men wrested control of the colonies from Indigenous people through short fights or by scaring them with their ships, weapons, and trade goods. For example, Columbus had a crew of 90 men on his famous voyage in 1492. He left 39 of them behind to build a settlement in what is now Haiti.

Colonialism attracted European countries because it enabled them to expand their territory and gain profits. They were also able to recruit and often enslave Indigenous people for the benefit of the colonizing nation.

In Brazil, explorers known as bandeirantes went on expeditions to find Native people. They aimed to capture and enslave them for plantations and mines set up by the Portuguese.

Slavers from throughout Europe participated in the Atlantic slave trade. They dealt in kidnapped Central and West Africans and forced them to perform labor that enriched their empires overseas.

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Even former colonies eventually became colonizers themselves. Once held by Great Britain, the United States extended its territory shortly after winning the War of Independence. It later expanded its claims to the Pacific and Latin America.

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Beginning in the 1880s, European nations took over African countries for their coveted natural resources and raw materials. They set up colonies that lasted until decolonization. This period occurred from 1914 to 1975 and challenged European control.

By far, the British government was the most successful colonizer. At its height soon after World War I, it claimed territories in every time zone in the world. The sun “never set” on the British Empire’s political and economic ambitions, which it carried out with the help of British colonial governments.

Despite the growth of European colonies in the Western Hemisphere, most colonized countries gained independence in the 18th century and into the 19th century. This began with the American Revolution in 1776 and the Haitian Revolution in 1781. However, the Eastern Hemisphere continued to tempt European colonial powers.

Colonial powers justified their conquests by claiming they had a legal and religious obligation to control the land and culture of Indigenous peoples. Conquering nation states saw themselves as civilizing “barbaric” or “savage” countries. They argued they were acting in the best interests of those they exploited.

Historically, church leaders encouraged and participated in taking over other lands and exploiting labor. They often did this to convert people to Christianity.

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In the 15th century, Catholic popes laid out a religious justification for colonization. They issued a series of papal bulls now known as the Doctrine of Discovery. It asserted that colonization was necessary to save souls and seize lands for the growth of the Church.

Often, Christian missionaries were among the first to make inroads into new lands. They imported both religious and cultural customs and a paternalistic attitude toward the colonies’ Native inhabitants. They believed that they must convert as many Indigenous people to Christianity as possible.

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Yet resistance to this control is an integral part of the story of colonialism. Even before decolonization, Indigenous people on all continents staged violent and nonviolent resistance to their conquerors.

In 1680 the Pueblo Rebellion overthrew Spanish rule of what is now New Mexico. In 1791, the slave revolt in Haiti turned into a revolution. In the 1800s, a series of rebellions fought the British Raj’s colonial rule in India.

Thanks to a series of savvy alliances, Ethiopia was one of just two African nations able to avoid European colonial rule. In 1896 the nation managed to stave off an Italian invasion at the Battle of Adwa.

Colonial governments invested in infrastructure and trade and disseminated medical and technological knowledge. In some cases, they encouraged literacy, the adoption of Western human rights standards, and sowed the seeds for democratic institutions and systems of government.

Some former colonies, like Ghana, experienced a rise in nutrition and health with colonial rule, and colonial European settlement has been linked to some development gains.

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However, coercion and forced assimilation often accompanied those gains, and scholars still debate colonialism’s many legacies. Colonialism’s impacts include environmental degradation, the spread of disease, economic instability, ethnic rivalries, and human rights violations. Such issues can long outlast one group’s colonial rule.

As South Asia historian John McQuade wrote in The Conversation: “It takes a highly selective misreading of the evidence to claim that colonialism was anything other than a humanitarian disaster for most of the colonized.”