Gao is the greatest of the realms of the Sudan, the most important and most powerful. All other kingdoms obey its king.
—Al-Ya‘qubi, 9th century
Strategically positioned beside the Niger River and between the Sahara and the fertile West African Savanna, the city of Gao was an important center for trade in the Middle Ages. Abu ‘Ubayd al-Bakri (d. 1094), a medieval geographer and historian, observed that Islam was well established in Kawkaw, the Arabic name for the kingdom of Gao, in the 11th century the town consists of two towns, one being the residence of the king and the other inhabited by Muslims.
Gao Ancien was the royal capital and residence; five miles east was the Muslim town, Gao Saney. Several tombstones with Arabic inscriptions have been found in a cemetery on the outskirts of Gao Saney. This pattern of twin communities in capitals of chiefdoms or kingdoms where the king was not Muslim was replicated throughout much of West Africa, especially along routes of the caravan trade.