The vast territorial extent of the Achaemenid Empire is often assumed to have impeded connectivity and communication within the empire. This paper challenges the validity of this assumption. Two factors in particular favor this conclusion—the presence of an extensive road network and the high communication speed in the empire, made possible by the pirradazish service. Together, they demonstrate the enormous potential for movement and interaction throughout the empire. The Achaemenid Empire was among the largest empires of the ancient world . It covered a land area five times greater than any of its predecessors and was matched, later, only by the Xiongnu confederation and the Han Dynasty in China. Although its size is frequently commented upon, the impact of the empire’s geography on its overall character and its day-to-day operations has rarely been articulated. Most scholarship assumes implicitly that the empire’s size inhibited connectivity and communication. Robin Lane Fox, in his biography of Alexander, went so far to as to write that “centralized rule is the victim of time and distance and in an empire where a royal letter could take three months to go from Phrygia to the Persian Gulf, power had to be local to avoid dilution by mountains and slow roads” This remark encapsulates neatly the effects of such assumptions: local political autonomy was a necessity, cultural and economic interactions were limited, and rebellions were frequent, in the absence of strong imperial oversight. In this article, with awareness of geographical differences, the postal and communication system of the Achaemenid Empire is compared with the existing structure in Rome and the Pony Express in America, to better understand this structure in this vast kingdom.