From Assimilation to Multiculturalism: Changing Models of Majority-Minority Relationships in National Constitutions, 1789-2015 Ever since the emergence of the nation-state model in the late eighteenth century, many polities have pursued congruence between political and cultural units. As popular sovereignty became the main source of legitimacy in Western polities, centralized governmental projects to promote a national culture engulfed peripheral ones to produce increasingly homogeneous nations throughout the nineteenth and early twentieth century.