This is a comparative and qualitative study that falls under the categories of political philosophy and philosophy of religion. Its aim is to explore ancient Greek, Roman, Sanskrit, and Old Persian texts to uncover the concept of republicanism. It seeks to address several key questions: why republicanism appears to be a Western phenomenon, how the concept of natural law gave rise to Aristotelian politeia (a mixed form of government serving as the foundation of republicanism), how Divine Law and positive law were distinguished and kept separate within the Western tradition, thereby laying the groundwork for the 'Rule of Law,' and why the separation of Divine Law and positive law never occurred in Iran since the Sasanian dynasty of the 3rd century AD. This research asserts that the fusion of these two sets of laws in Iran has obstructed any possibility of republicanism and the establishment of positive law since the 3rd century.