Humans have always moved. Our species spread out of Africa and across every continent but Antarctica long before writing existed. This level looks at the last five centuries, when migration became global, when some of it was brutally forced, and when states built the border controls we now take for granted.
Forced migration on an ocean scale
The largest forced migration across the sea in history was the Atlantic slave trade. Between the early sixteenth and mid nineteenth centuries, about 12.5 million Africans were forced aboard ships bound for the Americas, and roughly 10.7 million survived the crossing. Their descendants now make up large parts of the populations of Brazil, the Caribbean and the United States. Any history of migration that begins with voluntary travellers leaves out the people who had no choice at all.
When Britain abolished slavery in its empire in 1834, plantation owners looked for new labor. Over the next eight decades more than a million indentured laborers, most of them from India, were shipped to Mauritius, the Caribbean, Fiji and South Africa on contracts that bound them for years. Conditions were often harsh, and critics at the time called the system a new form of slavery. It ended in 1917 after long campaigns in India.
The age of mass migration
Between about 1820 and 1920, some 50 million or more Europeans emigrated, most to the Americas. Steamships made the Atlantic crossing take days instead of weeks. The Irish famine of 1845 to 1852 killed about a million people and drove at least as many abroad. Italians, Poles, Scandinavians, Germans and Jews from the Russian Empire followed. From 1892 the federal station at Ellis Island in New York processed most new arrivals, eventually about 12 million people. In 1883 the poet Emma Lazarus wrote the lines later placed at the base of the Statue of Liberty: "Give me your tired, your poor, / Your huddled masses yearning to breathe free."
Europe was not the only source. Between the 1840s and the 1930s, tens of millions of Chinese and Indian migrants moved to Southeast Asia, the Indian Ocean islands and beyond, to work on plantations, in mines and in ports. And many migrants went home again: a large share of Italians who crossed the Atlantic eventually returned, some of them several times. Migration was often a circuit, not a single journey.
For most of this era, a European could board a ship with no passport at all. Passports and visas became routine only during and after the First World War, when governments at war wanted to track who crossed their borders and kept the controls once peace came.
The age of restriction
Openness was never equal for all. The Chinese Exclusion Act of 1882 was the first major American law to bar immigrants by nationality. Australia's Immigration Restriction Act of 1901 used a dictation test, which officials could give in any European language, to keep out non-Europeans. In 1924 the United States passed the Johnson-Reed Act, which set national origins quotas favouring northwestern Europe and sharply cut arrivals from southern and eastern Europe. Those quotas stood until 1965. Restrictions of this kind remind us that border rules have often been drawn along lines of race and religion.
Unmixing peoples
The twentieth century added a new kind of movement: states deliberately sorting populations. In 1923 Greece and Turkey agreed to a compulsory exchange that moved about 1.2 million Orthodox Christians from Turkey and roughly 400,000 Muslims from Greece. The exchange sorted people by religion, not by the language they spoke, so many Greek-speaking Muslims went to Turkey and Turkish-speaking Christians to Greece. The partition of India in 1947 uprooted perhaps 15 million people amid mass killing, and the Second World War left tens of millions displaced across Europe and Asia, the crisis that produced the modern refugee system in Level 3.
Worked example: Germany's guest workers
After the war, West Germany's economy grew so fast that it ran short of workers. Starting with Italy in 1955 and Turkey in 1961, it signed recruitment agreements with several countries. The workers, called Gastarbeiter or guest workers, were meant to come for a few years, earn money and go home. Policy assumed rotation: one cohort would leave as the next arrived.
Employers disliked training new workers every few years, and the workers themselves put down roots. When recruitment stopped in 1973, during an oil crisis and recession, the expected return did not happen. Many guest workers stayed and brought their families, partly because leaving meant they could never come back. The Swiss writer Max Frisch summed up the lesson in a famous remark: governments had sent for labor, and human beings had arrived instead.
For decades German law treated these families as foreigners, even children born and raised in Germany. Citizenship reform came only in 2000, a story Level 7 picks up. The pattern is common: temporary labor programs tend to become permanent settlement, because the people in them build lives. Planning that ignores this tends to produce long periods in which settled residents have no political voice.