Slavery was a mainstay of the Brazilian colonial economy, especially in mining and sugarcane production. 35.3% of all slaves involved in the Atlantic Slave trade went to Brazil. 4 million slaves were obtained by Brazil, 1.5 million more than any other country. Starting around 1550, the Portuguese began to trade African slaves to work the sugar plantations, once the native Tupi people deteriorated. Although Portuguese Prime Minister Sebastião José de Carvalho e Melo, 1st Marquis of Pombal abolished slavery in mainland Portugal on 12 February 1761, slavery continued in her overseas colonies. Slavery was practiced among all classes. Slaves were owned by upper and middle classes, by the poor, and even by other slaves.