In Angola however, black Africans never made up less than 95% of the population, so the demographic situation there (and in the other Portuguese colonies) was never the same as it was in Brazil. Furthermore, the claim that racial mixing equates to racial egalitarianism is problematic, as there are significant racial inequities in Brazil and other countries with large mestiço populations. The fact that the Portuguese were leaders in international trade of African slaves for nearly 400 years also challenges the theory. Despite its ostensibly obvious contradictions, lusotropicalism was widely accepted among the people of Portugal until the mid-1970s, and was used by the government to justify its continued involvement in Africa during a period when most European powers were leaving or had already left the continent. These colonial policies of the twentieth century instigated the forty years of conflict in Angola.  However, a long history of violence and exploitation created the context for these struggles, starting with the Atlantic slave trade in the late fifteenth century. 	
After Vasco de Gama secured a passage to India at the turn of the sixteenth century, Portugal lost interest in Kongo and other African kingdoms as major trading partners, and began to view them primarily as sources of slaves. The slave trade came to dominate Portuguese-African relations and nearly all economic activity in Angola. As a highly lucrative business, it was often the primary occupation of most Portuguese in the area, including members of the colonial administration, with the governor essentially the largest slave-dealer. The Portuguese were leaders in the Atlantic slave trade, supplying not only their own plantation-dependent colonies with labor, but also those of France, Britain, and Spain. According to some estimates, as many as 8 million slaves were taken from Angola, a figure higher than the total population of the country upon independence in 1975. The slave trade caused major disturbances in the interior, with the associated violence and depopulation ultimately leading to the demise of the Kongo and other indigenous states. 
The abolition of the international slave trade in the 1830s and of slavery throughout the Portuguese empire in the 1870s did not mark the end of forced African labor in Angola. Domestic slavery, particularly among the Kongo chiefs and highland kings of the interior was still widespread and slaves continued to be exported to Indian Ocean markets further east. Forced labor continued in a legal form under the new system of forced labor outlined in the 1878 Regulamento para os contratos de serviçais e colonos nas províncias de África (Regulation for contracts of servants and colonists in the provinces of Africa). This document essentially made former slaves into “servants” or serviçais, who had to be “contracted” into labor. The Regulamento also stipulated that any Angolans who were not fully employed were considered “vagrants” and could be legally forced into five-year contracts. While slaves were no longer exportable commodities on the same scale they were before the abolition of the slave trade, slavery persisted in much the same way it had in the past centuries, despite the change in nomenclature. 