The area of the Republic of Ghana became known in Europe and Arabia as the Ghana Empire after the title of its Emperor, the Ghana. Geographically, the ancient Ghana Empire was approximately 500 miles (800 km) north and west of the modern state of Ghana, and controlled territories in the area of the Sénégal River and east towards the Niger rivers, in modern Senegal, Mauritania and Mali. The empire appears to have broken up following the 1076 conquest by the Almoravid General Abu-Bakr Ibn-Umar. A reduced kingdom continued to exist after Almoravid rule ended, and the kingdom was later incorporated into subsequent Sahelian empires, such as the Mali Empire. Around the same time, south of the Mali empire in present-day northern Ghana, the Kingdom of Dagbon emerged. The decentralised states ruled by the tindaamba were unified into a kingdom. Many sub-kingdoms would later arise from Dagbon including the Mossi Kingdoms of Burkina Faso and Bouna Kingdom of Ivory Coast. Dagbon pioneered Ghana's earliest learning institutions, including a university town, and a writing system prior to European arrival.