Numismatic evidence for contact between Rome and the Kushans is particularly strong. The Kushan king Vima Kadphises (r. c. 80-c.120) introduced coinage that in look and size closely resembled the Roman aureus, which was gold, unlike the earlier copper coinage. There was no source of gold within the Kushan domain.
Dio Cassius records that an Indian delegation approached Trajan to request gold. These were probably Kushans. As a result of the Second Dacian War, Trajan had acquired 5,000,000 pounds of gold and twice that much of silver. Thorley thinks Rome agreed and signed a treaty with the condition that they receive the commodities they wanted, silk and luxury goods, including fur and jewelry. India acted as intermediaries in the sale of silk, trading with China for it in order to sell it to the west. Kushan King Huvishka, the second to last Kushan king, minted coins with an image of the goddess Roma posed as Minerva. Before Huvishka, King Kanishka II used the title KAISAR on an inscription.
Thorley believes the Kushans may have controlled the silk trade as a government monopoly, possibly from Bergram.