Djenné is the oldest known city in sub-Saharan Africa. Founded between 850 and 1200 A.D. by Soninke merchants, Djenn served as a trading post between the traders from the western and central Sudan and those from Guinea and was directly linked to the important trading city of Timbuktu, located 400 kilometers downstream on the Niger river. It was captured by the Songhai emperor Sonni 'Ali in 1468. Historically, Djenn was known as a center of Islamic learning, attracting students from all over the region who were followers of the Moslem faith. A very large number of terracotta sculptures and vessels have been found in the Inland Delta of the Niger River area of Mali, which date from the last centuries of the first millennium A.D. through the 15th century. The style is often referred to as the "Djenné" style, named after a city that rose to prominence in this area in approximately 500 A.D. and experienced great prosperity until the end of the 15th century.