In a short, narrative report that does not fit into a specific time frame, Herodotus talks about the Achaemenids' damming of the waterways of the Chorasmian civilization, which, in his view, caused hardship for the people and limited their access to water, and as a result, the Achaemenid king opened the water to the people in exchange for taxes. The fictional nature of this account and Herodotus' negative view of these water supply systems have prevented researchers from examining it independently, although a closer examination shows that important historical themes can be extracted from it. The present research, which will be conducted using content analysis and archaeological methods, seeks to answer the question: What is the historical context of Herodotus's narrative of Darius' dam-building in Chorasmia? The findings will show that Herodotus' report can be attributed to the period of Darius I’s reign, between 519 and 513 BC; the purpose of constructing these water supply systems was to expand the cultivated land in Chorasmia and thereby increase the income of the central government. The type of dams described by Herodotus is similar to Achaemenid examples found in Persia, and his description of water flow management is also consistent with the administrative and economic structure of the Achaemenid empire as we know it from primary sources and therefore, we can consider the original Herodotus' report to be of historical nature and place it within the framework of Darius I's economic and tax reforms.