The main and basic elements of international law clearly existed in some civilizations, especially ancient Iran. Based on historical evidence, it is possible to extract the existence of general legal principles regarding the regulation of relations between the ancient Iranian empire and other governments and foreign nationals. Examining the evidence left from the Achaemenid period, shows the semantic and conceptual affinity of the political-legal culture governing the behavior of the Achaemenid kings with the modern concepts of international law; Considering the predominance of semanticism in the worldview and epistemology of ancient Iran, this shows the capacity and capability of approaches based on natural law theories with regard to global governance and can be an option for refining the international legal system based on positivist theories. This historical-analytical research can be a basis to review and recognize some of the most important propositions of contemporary international law.