 After independence, during the existence of the Kingdom of Portugal, the country played a leading role in the Atlantic Slave Trade, which involved the mass trade and transportation of slaves from Africa and other parts of the world to the American continent.Slavery was abolished in Portugal in 1761 by the Marquês de Pombal.After the abolishment of slavery in Portugal, the Portuguese slave traders turned to clients in other countries where slavery was not yet abolished such as the United States of America.