The roots of IOs can be traced back to the emergence of the modern international system after the Peace of Westphalia in 1648. Because the early international system had been mainly dominated by European nation states, first IOs emerged in the 19th century in Europe. The Congress of Vienna (1815) created a more convenient atmosphere for the development of IOs. The role and place of the state in the system also changed as a result of the development of communication systems. Therefore, it became necessary to define the changing nature of the international system and the role of power and states in international affairs. With the involvement of the different types of actors, the international system has become more complicated and interdependent.