The Persian people called Darius a ‘merchant’ as an acknowledgement for his ability to renovate the administration and economy of the empire. The introduction of a number of schemes to promote the economy has led to an unprecedented prosperity in all parts of the empire which lasted for half a century. Darius introduced coinage and a uniform system of weights and measures to create a simple trade system. He also fixed inequalities of taxation and tribute which provided support to improve of the overall being of the empire.
The introduction of a standard imperial coinage (daric and sigloi) and a uniform system of weights and measures (karshas, halurin, quarters and shekels) has greatly benefited the empire because it made the transfer of wealth amongst people easier and safer. Although Croesus of Lydia was the original creator of coinage, Darius has ensured its adoption by most of the civilised world. The coins were used as an instrument of propaganda as the coins shows an image of the king in a crouching position with royal robes, crown, carrying a spear, quiver and a bow to depict the Persian’s powerful ruler. There were numerous trade routes within the empire that facilitated trade throughout the empire, the main one was the Royal Road. It connected parts of the empire from Sardis in the west to Susa, the main treasury of the empire. The trade routes and coinage has allowed the exchange of goods from one part of the empire faster and safer as Persians usually transfer goods in bulk. It was also easier to exchange with coinage for goods because the exchange of talents required a scale to weigh the metals and assaying to determine its purity. Persians invested in a number of seafaring expeditions and voyages to attain more natural resources and new trade markets. Completion of the Suez Canal under Darius allowed effective trade in the southern seas. A stela has been found