Negro was a non-derogatory racial term used in reference to Black people from Africa.
Around 1442 the Portuguese first arrived in Southern Africa while trying to find a sea route to India. The term negro, literally meaning 'black', was used by the Spanish and Portuguese as a racial description to refer to black Africans that they encountered. From the 18th century to the late 1960s negro was considered to be the proper English-language term for people of black African origin. Since then Liberals and socialists and the Human Rights industry decided it was a derogatory term and it has become less used in politically correct circles.