Turning to history has always been an important tool for understanding international relations, and this trend remains relevant today. However, if earlier researchers mainly focused on individual events and their possible interpretations, now the main attention is focused on determining the historical characteristics of systems and reflecting this legacy in modern international relations. That is why the postcolonial approach, focused on the gradual evolution of colonial relations into the modern system of international relations, has become especially important; postmodernism is used to explain the concept of postcolonialism. In these concepts, an important place is occupied by the terms colonialism and postcolonialism, which seem to be a continuation of each other, despite the fact that they oppose each other. This article explains some of these concepts. Looking at the development and theoretical history of the concept of postcolonialism, it can be concluded that the concept was first used by Edward Said in his work entitled “Orientalism”. In Edward Said's “Orientalism” (1978) [Said, 1978], although many derivative terms from the concepts of colonialism and imperialism are used, the word postcolonialism does not appear even once in this work. No less important than Edward Said's research into the consolidation of postcolonialism as a concept is Subaltern Studies, first developed by Indian Marxist historians in 1982. Thus, although postcolonialism has not yet reached its final form in terms of naming, thanks to the book "The Empire Writes Back" [Ashcroft, Griffiths, & Tiffin, 1989] published in 1989, today both the term and the theoretical concept are used in modern scientific circles.