Under the government of Mansa Musa, who became emperor of Mali in 1307, Timbuktu turned into the most important religious and commercial center of the Islamic culture in Sub-Saharan Africa, as well as into a well-known intellectual center for Islamic studies. Architects and builders were brought there to build primarily large mosques, libraries and educational institutions known as madrasas, as well as an university. One of those architects was Abu Es Haq es Saheli, who built the famous Djinguereber Mosque. This building, which was erected in 1327, is in large part made of earth and organic materials, and in 1988 it was inscribed on the list of UNESCO World Heritage Sites.