in fact, not all favelas in rio de janeiro originated in the same way - some of rio's older favelas, also called 'mocambos' or 'quilombos,' were urban areas occupied by freed or escaped african slaves and other minorities, who had no other place to live.    

some favelas originated as settlements of farmers and european immigrants, such as  the favela rocinha .  ' rocinha ' translates as 'little farm.'     

a few favelas rose out of run-down development projects and public housing complexes, such as cidade de deus (city of god).  these housing projects were intended to be better homes to residents in favelas deemed to be illegal, unsafe, or that were destroyed by natural events.   

other favelas, especially in the zona sul, started as simple housing complexes specifically designed to be the home of the workers providing services to the nearby high-income areas.