36 Historiography has amply referred to the problem of ethnic identities, particularly the relationship between the categories derived from mixed races and the "society of castes" and the social structure of the colonial American world. In general terms, we can point out that the initial impact of the statements of Magnus M?r that established equivalence between "race" and social hierarchies have been questioned from different angles. The criticisms on the nomenclature used, like "race" or "ethnia", do not only express semantic problems, but they pretend to show the ambiguity of cultural identities and the inconveniences of circumventing the tight links between those categories and the mechanisms of domination used by Hispanics. Some examples: Magnus M?r, La mezcla de razas en la historia de Am?ca latina, Buenos Aires, Paid?1969;
