From its origins as a minor nomadic tribe to its status as a major world empire, the rise of the Parthian state in the ancient world is nothing short of remarkable. In their early history, the Parthians benefitted from strong leadership, a flexible and accommodating cultural identity, and innovative military characteristics that allowed them to compete against and even overcome Greek, Persian, Central Asian, and eventually Roman rivals. Reign of Arrows provides the first comprehensive study, in almost a century, dedicated entirely to early Parthian history. Assimilating a wide array of especially recent scholarship across numerous fields of study, Nikolaus Overtoom presents the most cogent, well rounded, and up-to-date account of the Parthian empire in its wider context of Hellenistic history. It explains the political and military encounters that shaped the international environment of the Hellenistic Middle East from the middle third to the early first centuries BCE. This study combines traditional historical approaches, such as source criticism and the integration of material evidence, with the incorporation of modern international relations theory to better examine the emergence and expansion of Parthian power. Relevant to historians, classicists, political scientists, and general readers interested in the ancient world and military history, Reign of Arrows reimagines and reconstructs the rise of the Parthians within the hotly contested and dangerously competitive international environment of the Hellenistic world.