Political Economy assumed the definition of the study of economies of polities or nation states in the 18th century. Gradually, the concept of the Physiocrats' that land was the source of all wealth was surpassed by the labor theory of value supported by John Locke, Adam Smith and Karl Marx. Notably, Political Economy incorporates liberal, realist. Maxian and constructivist theories from political science. Starting from the 19th century. "economics" or the study of the economy replicated the term "political economy" The latest version of the term i.e. International Political Economy(IPE). among other things, studies the effect of domestic monetary and fiscal policies on international trade and finance in relation to a specific country. Extensive use of rational choice assumptions and game theory are an integral part of the study of lPE in today's world.