The practice of differentiating between individuals is a feature that knows neither spatial nor temporal limitations. With the organisation of human beings into societies came the development of oppositional relationships: there have been leaders and followers, rulers and ruled, worldly and spiritual authorities, those who owned the land and those who worked on it. There have been those who possessed social, economic and political capital, and those who did not. According to the context, the reasons why these relationships developed and were sustained varied greatly. Often, further differentiation occurred inside differentiation. For example, wielding a sword or a plough was not the only determining factor, but also if one was a man or a woman, or if one believed in one religion or the other. From the seventeenth century onwards, differentiation based on race was added to the equation.

Being part of one group – whatever the group and the criteria for being included were – had a dual effect: it meant simultaneously belonging but also estrangement. At the risk of taking away the complexity from the matter, when the inclusion in or exclusion from a group entailed unequal treatment (in reference to other groups), then one talks not only of differentiation but also of discrimination. The simultaneous existence of several patterns of differentiation inside a given society makes the analysis of discrimination a convoluted undertaking, in which defining the concepts one uses becomes of crucial importance. An enquiry into Japanese history is no exception. Certainly, as in every society, there have been instances of economic, social, gender and racial discrimination. Equally certain, it is often difficult to distinguish between these, as the ways in which these occurred often overlapped. Yet, it is possible to do so, with the prerogative, however, to conceptually frame the object of enquiry. Not doing so invites the hazard of wrongly ascribing peculiar types of discriminations to the wrong causes.

Exemplary of this problem is the attribution of a racist character to the society of Tokugawa Japan. Historian Herman Ooms, for example, asserted the existence of an ‘intra-race racism’ aimed at the eta and hinin outcasts and fostered by the authorities. The cultural anthropologist Takezawa Yasuko argued in a similar vein that these groups were at the margins of the Tokugawa society and were victims of racial discrimination.