Internal colonialism is the uneven effects of economic development on a regional basis, otherwise known as "uneven development" as a result of the exploitation of minority groups within a wider society which leads to political and economic inequalities between regions within a state. This is held to be similar to the relationship between a metropole and a colony, in colonialism proper. The phenomenon leads to the distinct separation of the dominant core from the periphery in an empire. Robert Blauner is regarded as the developer of the theory of internal colonialism. The term was coined to highlight the "blurred" lines between geographically close locations that are clearly different in terms of culture. Some other factors that separate the core from the periphery are language, religion, physical appearance, types and levels of technology, and sexual behavior. The cultural and integrative nature of internal colonialism is understood as a project of modernity and it has been explored by Robert Peckham in relation to the formation of a national modern Greek culture during the nineteenth century, when Greece gained its independence from the Ottoman Empire. The main difference between neocolonialism and internal colonialism is the source of the exploitation. In the former, the control comes from outside the nation-state, while in the latter it comes from within. The first known use of the concept of internal colonialism was by regarding South Africa. However, the concept became popularized following the publication of an article on Mexico by . Gonzalez Casanova was both critiqued by, and influenced Andre Gunder Frank, who further theorised internal colonialism as a form of "uneven development". Sergio Salvi, a poet, essayist, and historian of minority languages, used the term "internal colonies" in the cultural sense in Le nazioni proibite: Guida a dieci colonie interne dell'Europa occidentale ("The forbidden nations: Guide to ten internal colonies of western Europe") (1973), among which he included Catalonia, Scotland, Brittany and Occitania.