What group of people was taken and sold as slaves?

What does this answer mean?

Africans were taken and sold as slaves. USCIS accepts "Africans" or "people from Africa."

People were captured in Africa and carried across the Atlantic Ocean in the slave trade. In 1619, a group of about 20 Africans was brought to the English colony of Virginia, an early step in the history of slavery in what became the United States. Over time, slavery grew and became part of the law in the colonies.

Congress banned bringing enslaved people into the country starting in 1808, but that law didn't end slavery itself or the buying and selling of enslaved people within the United States.

Slavery was a central cause of the Civil War. It finally ended with the 13th Amendment, ratified in 1865. Several other questions on the test connect to this history, including the Emancipation Proclamation, the Civil War, and the civil rights movement.

At the interview, say "Africans" or "people from Africa."