Human arrival in Ivory Coast (officially called Côte d'Ivoire) has been dated to the Upper Paleolithic period (15,000 to 10,000 BC), or at the minimum, the Neolithic period based on weapon and tool fragments, specifically polished shale axes and remnants of cooking and fishing. The earliest known inhabitants of Côte d'Ivoire left traces scattered throughout the territory. Historians believe these people were all either displaced or absorbed by the ancestors of the present inhabitants. Peoples who arrived before the 16th century include the Ehotilé (Aboisso), Kotrowou (Fresco), Zéhiri (Grand Lahou), Ega, and Diès (Divo). Little is known about the original inhabitants of Côte d'Ivoire. The first recorded history is in the chronicles of North African Muslims who conducted a caravan trade across the Sahara in salt, slaves, gold, and other items from early Roman times. The southern terminals of the trans-Saharan trade routes were located on the edge of the desert, and from there, supplemental trade extended as far south as the edge of the rainforest. The more important terminals—Djenné, Gao, and Timbuctu—grew into major commercial centers around which the great Sudanic empires developed. These empires dominated neighboring states by controlling the trade routes with powerful military forces. The Sudanic empires also became centers of Islamic learning. Islam was introduced into western Sudan by Arab traders from North Africa and spread rapidly after the conversion of many important rulers. By the 11th century, the rulers of the Sudan empires had embraced Islam that spread south into the northern areas of contemporary Ivory Coast. Ghana was the earliest of the Sudan empires; it flourished in present-day eastern Mauritania from the fourth to the 13th century. At the peak of its power in the 11th century, its realms extended from the Atlantic Ocean to Timbuctu. After the decline of Ghana Empire, the Mali Empire grew into a powerful Muslim state, reaching its peak in the early 14th century.