Djenne, the oldest known city in sub-Saharan Africa is situated on an island in the Bani River, in central Mali. It was a prospering city from the 14th until the 16th century, when it acted as an important station on the Trans-Sahara route. Djenne was also known as a center of Islamic learning and pilgrimage, attracting students and pilgrims from all over West Africa. Its Great Mosque dominates the large market square of Djenne. Tradition has it that the first mosque was built in 1240 by the sultan Koi Kunboro, who converted to Islam and turned his palace into a mosque. Very little is known about the appearance of the first mosque, but it was considered too sumptuous by Sheikh Amadou, the ruler of Djenne in the early nineteenth century.