The role of theories and knowledge more generally is to reveal what is real and what is an illusion. Historical materialism – the theory that drives Marxism – tries to apply this advice by grounding the understanding of international relations in the ways in which people have transformed the land, produced things on it and are ultimately dependent on its resources for shaping political institutions such as the state and international organisations. Marxism has made several inroads in the development of the discipline of IR by being intrinsically concerned with the ways in which people – and groups – interact and produce things across borders, as well as how they organise themselves through institutions to manage and contest the production and distribution of things across the world. More specifically, it argues that the construction of modern borders is determined by, or linked in various ways to, the development of capitalism. Therefore, it makes us question the natural or inevitable character we tend to ascribe to our economic and political systems. In other words, if a system is not as real and fixed as we first thought, because it has a particular and relatively short history in the broader course of humanity, then it becomes much easier for us to imagine the various ways it is challenged and how it could be transformed to a system that, Marxists hope, will better redistribute the wealth of the world. Marx himself wrote that philosophy is often too concerned with interpreting the world, when the real point is to change it. Marxism as a theory of IR has certainly answered that call and, regardless of variations within the theory family, to be a Marxist always means to challenge one’s ideas about the world.