 Marriage and any sexual relations between the upper strata "fotsy" and the lower strata "mainty" were a taboo.According to a 2012 report by Gulnara Shahinian – the United Nation's Special Rapporteur on contemporary forms of slavery, the descendants of former slave castes continue to suffer in contemporary Madagascar Merina society, and inter-caste marriages continue to be socially ostracized.The caste systems in Africa have been linked to the a pre-developed trading network, invasions from North Africa and the Middle East after the 7th century, followed by a slavery system that targeted the pagans.