 Initial relations between Portugal and Kongo were respectful, with both sides exchanging ambassadors and gifts. Within twenty years members of the Kongo royal family, including the king, had adopted Catholicism and encouraged Portuguese missionaries to spread the faith among the people. 
However, this relationship soon became strained as the trade in slaves became the primary interest and occupation of the Portuguese in Africa. By 1575 more than 400,000 slaves had been exported, primarily to the plantation-based colonies of São Tomé and Brazil, as well as to other New World colonies.  The effects of the slave trade severely weakened the Kongo state and removed nearly all vestiges of the friendly relationship and interest in Portuguese religion and culture that existed upon contact. Until the late nineteenth century Portugal’s presence in Angola was mostly limited to the coast, and much of the territory was controlled indirectly through semi-autonomous fiefdoms held by African allies or mestiços of mixed European and African descent. Because the European population was so small, mestiços, also known as Afro-Portuguese, performed key roles in the military, civil service, and business, occupying a privileged social position above the indigenous Africans and below the Portuguese. The Afro-Portuguese were also heavily involved in the slave trade, which dominated nearly all economic activity in Angola prior to its abolition in the 1870s.
	At Berlin Conference of 1884–1885 the European powers divided most of Africa into zones of influence, as they competed for influence and dominance of the continent. The so-called “scramble for Africa” was brought about by the industrialization of Europe and the need for both important natural resources and markets for finished industrial goods. Like its neighbors and rivals, Portugal asserted its hold over its colonies in this period and began to develop and settle the interior. 
	New attempts to start plantations and agricultural settlements in the interior mostly failed, but a greater number of Portuguese settlers, mainly impoverished peasants, immigrated to the colony, settling primarily in the cities along the coast. As the number of whites in the cities increased, they began to displace the mestiços, and new restrictions were placed on bureaucratic positions. By the 1920s the old Afro-Portuguese elite had mostly lost its prominent place it had occupied during the nineteenth century. The dissatisfied members of this group would form much of the leadership of the various rebel groups during the liberation war.
	Though the European population in Angola was rising it wasn’t until after World War II that large scale white immigration began. The war had been a successful period for neutral Portugal, and the economy of Angola grew as demand for tropical commodities increased, and Portuguese exploitation of African labor was expanded. Under the system of forced labor, African groups were moved around the country, causing conflicts between the displaced tribes which would continue into the modern era. Unlike industrial France and Britain, Portugal was relatively poor and undeveloped and thus more dependent on its overseas possessions for its economic well-being. 