The origins of sovereignty lie in the political and intellectual history of the Middle Ages, where a number of different, but not mutually exclusive, understandings of sovereignty emerged: ruler sovereignty, state sovereignty and popular sovereignty. At first international law was concerned almost exclusively with state sovereignty. In the twentieth century, however, the idea of popular sovereignty entered international law in the form of the principle of self-determination. In a normative sense – and increasingly a doctrinal one too – state sovereignty and popular sovereignty are intertwined. Arguments about the demise of the State and the irresistible rise of supranationalism have often failed to take into account the resilience of sovereignty and its transformation.