Term used in international relations, supposedly arising from the Treaties of Westphalia in 1648 which ended the Thirty Years War. It is generally held to mean a system of states or international society comprising sovereign state entities possessing the monopoly of force within their mutually recognized territories. Relations between states are conducted by means of formal diplomatic ties between heads of state and governments, and international law consists of treaties made (and broken) by those sovereign entities. The term implies a separation of the domestic and international spheres, such that states may not legitimately intervene in the domestic affairs of another, whether in the pursuit of self‐interest or by appeal to a higher notion of sovereignty, be it religion, ideology, or other supranational ideal. In this sense the term differentiates the ‘modern’ state system from earlier models, such as the Holy Roman Empire or the Ottoman Empire.