The Republic of Ghana is named after the medieval West African Ghana Empire. The empire became known in Europe and Arabia as the Ghana Empire after the title of its Emperor, the Ghana. 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 several centuries later. 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. In central Sub-Saharan Africa, agricultural expansion marked the period before 500 AD. Farming began earliest on the southern tips of the Sahara, eventually giving rise to village settlements.Toward the end of the classical era, larger regional kingdoms had formed in West Africa, one of which was the Kingdom of Ghana, north of what is today the nation of Ghana. Before its fall at the beginning of the 10th century, Akans migrated southward and founded several nation-states around their matriclans, including the first empire of Bono state founded in the 11th century and for which the Brong-Ahafo (Bono Ahafo) region is named. The Mole-Dagbon people, who founded the earliest centralised political kingdoms of Ghana, migrated from Lake Chad to present day Ghana. Later, Akan ethnic groups such as the Ashanti, Akwamu, Akyem, Fante state and others are thought to possibly have roots in the original Bono state settlement at Bono Manso. The Ashanti kingdom's government operated first as a loose network and eventually as a centralized empire-kingdom with an advanced, highly specialized bureaucracy centred on the capital Kumasi. By the end of 16th century, most of the ethnic groups constituting the modern Ghanaian population had settled in their present locations. Archaeological remains found in the coastal zone indicate that the area has been inhabited since the Bronze Age (ca. 2000 BC), but these societies, based on fishing in the extensive lagoons and rivers, have left few traces. Archaeological work also suggests that central Ghana north of the forest zone was inhabited as early as 3,000 to 4,000 years ago. These migrations resulted in part from the formation and disintegration of a series of large states in the western Sudan (the region north of modern Ghana drained by the Niger River). Strictly speaking, Ghana was the title of the king, but the Arabs, who left records of the kingdom, applied the term to the King, the capital, and the state. The 9th-century Berber historian and geographer Al Yaqubi described ancient Ghana as one of the three most organized states in the region (the others being Gao and Kanem in the central Sudan). Its rulers were renowned for their wealth in Gold, the opulence of their courts, and their warrior/hunting skills. They were also masters of the trade in gold, which drew North African merchants to the western Sudan. The military achievements of these and later western Sudanic rulers, and their control over the region's gold mines, constituted the nexus of their historical relations with merchants and rulers in North Africa and the Mediterranean.