“The tariff certificates indicate that there were substantial trade exchanges in the region,” Ehsan Yaghmaii added.

Toll-e Bondu is located near Nurabad, 158 kilometers west of the provincial capital Shiraz.

“The tariff certificates are similar to modern-day jettons. Merchants of Toll-e Bondu certified their goods through the clay tariff certificates, and the number and quality of the commodities were inscribed on them,” Yaghmaii said.

The clay tariff certificates are the same size as a match box, he added.

The team of archaeologists had previously discovered over 5000 pottery works and shards and a large pottery workshop at the ancient site. Due to the evidence of mass production of pottery, archaeologists believe that the products were also exported to other regions.

Toll-e Bondu is situated between Marvdasht and Khuzestan Province, wherein some productions of the site were previously found. In fact, the people of Toll-e Bondu exported their products to Susa and Haft-Tappeh in Khuzestan and Marvdasht in Fars, experts say.

At the ancient site, the team also recently discovered an instrument which archaeologists believe is a pen dating back to the mid-Elamite era (1500-1100 BC).

The archaeological studies are being carried out by Kazerun Azad University and the Cultural Heritage and Tourism Organization.