The Iranian Empire emerged in the third century in the interstices of the Silk Road that increasingly linked the markets of the Mediterranean and the Near East with South, Central, and East Asia. The ensuing four centuries of Iranian rule corresponded with the heyday of trans-Eurasian trade, as the demand of moneyed imperial elites across the continent for one another's high-value commodities stimulated the development of long-distance networks. Despite its position at the nexus of trans-continental and trans-oceanic commerce, accounts of Iran in late antiquity relegate trade to a marginal role in its political economy. The present article seeks to foreground the contribution of trans-continental mercantile networks to the formation of Iran and to argue that its development depended as much on the political economies of its western and eastern neighbours as on internal Near Eastern factors.