However, at the root of the early failures of white settlement lied the Portuguese system of penal colonization.  As with overseas colonization in general, the Portuguese were the first to begin and the last to stop the practice of using convicts as settlers in their colonies.  The difficult nature of life in Africa made it difficult to find voluntary immigrants, so convicts, called degradados, were seen as an effective subsitute, as well as a solution to the problem of overcrowding in Portuguese prisons. 