At Unguja Ukuu, human activity transformed the coast of Zanzibar more than 1,000 years ago

The medieval settlement of Unguja Ukuu, on the Zanzibar Archipelago off the coast of Tanzania, was a key port in an extensive Indian Ocean trade network that linked eastern Africa, southern Arabia, India and Southeast Asia.

Our archaeological research shows how human activities between the seventh and twelfth centuries AD irreversibly modified the shoreline around the site. At first, these changes may have helped the trading settlement develop, but later they may have contributed to its decline and abandonment...