| Abstract: | This article combines historical analysis with international-relations theory to contend that geopolitical developments around the Eastern Mediterranean in the middle third century BCE were indirectly responsible for the emergence of the Parthian state and a new international system of states in the ancient East. Since the death of Alexander the Great, the Seleucid Empire had ruled over much of the East; however, disastrous military conflicts at home and abroad in the West caused a sudden decline of Seleucid power in the 240s–230s BCE. The troubles of the Seleucid state caused what political scientists call a power-transition crisis that damaged Seleucid hegemony over the East when the Seleucid satraps of Parthia and Bactria declared their independence. Moreover, the deleterious civil wars between Seleucid dynasts in the West and the rebellions of eastern satraps encouraged the nomadic Parni tribe from the Central Asian steppe (later known as the Parthians), who had been seeking a new homeland for decades, to invade northeastern Iran and establish a new kingdom. With the Parni's successful conquest of Parthia and its immediate consequences, a new interstate system of tripolarity between the Seleucid Empire, Bactrian Kingdom, and the newly formed Parthian state emerged in the ancient East. |
