Known. Harlaa was a busy trading town from the 10th to the early 15th century.
At Harlaa, in eastern Ethiopia, diggers found a mosque from the 12th century, with Islamic burials and headstones. In the ground were glass, rock crystal, carnelian, glass beads, cowrie shells, and pottery from Madagascar, the Maldives, Yemen and China. Bronze and silver coins from 13th-century Egypt were there too. Jewellers worked in silver, bronze, stones and glass beads. A grave complex held remains linked to about 300 people.
The page says no one knows what people gave in return for the materials used to make the jewellery.