When sparsely settled or easily conquered subtropical lands were found to the west, Europeans established plantations and saw Africans as ideally suited to forced labor in those environments. In the 1340s, the Portuguese found the Azores, Madeira, and Canary Islands off the west coast of Africa; they established sugar plantations worked first by natives and then by imported African slaves who were worked to death. In the 1500s, the Spanish and Portuguese imported this barbaric but profitable system to the West Indies and Brazil; the Dutch, French, and English would copy the model in areas suitable for growing sugar, tobacco, rice, and other plantation crops. Such treatment was justified in part by the ideology of the Crusades, which allowed unlimited war against (and exploitation of) non-Christians.
European laws generally distinguished between slavery and servitude, with the former permanent and the latter temporary, and limited slavery to war captives or condemned criminals. During the long Reconquista, the reconquest of the Iberian Peninsula, however, the Spanish and Portuguese became used to taking Muslim captives (some from North Africa) as slaves. By the thirteenth century, Iberian legal codes allowed for Muslim slaves and distinguished between a range of ethnic and religious categories based on ancestry and religion. Europeans also had been hardened to abuse and death by the system of feudalism and by wave after wave of epidemics, particularly the bubonic plague of the mid-fourteenth century. Most important to the development of slavery was the gradual evolution of the concept of race, which transformed Africans into a different type of human, somewhere on the Great Chain of Being between Europeans and animals.