<P> The rise of the Ghana Empire, now called Mali, Senegal, and southern Mauritania, paralleled the increase in trans - Saharan trade . Mediterranean economies were short of gold but could supply salt, taken by places like the African salt mine of Taghaza, whereas West African countries like Wangara had plenty of gold but needed salt . The trans - Saharan slave trade was also important because large numbers of Africans were sent north, generally to serve as domestic servants or slave concubines . The West African states imported highly trained slave soldiers . It has been estimated that from the 10th to the 19th century some 6,000 to 7,000 slaves were transported north each year . Perhaps as many as nine million slaves were exported along the trans - Saharan caravan route . Several trade routes became established, perhaps the most important terminating in Sijilmasa (Morocco) and Ifriqiya to the north . There, and in other North African cities, Berber traders had increased contact with Islam, encouraging conversions, and by the 8th century, Muslims were traveling to Ghana . Many in Ghana converted to Islam, and it is likely that the Empire's trade was privileged as a result . Around 1050, Ghana lost Aoudaghost to the Almoravids, but new goldmines around Bure reduced trade through the city, instead benefiting the Malinke of the south, who later founded the Mali Empire . </P> <P> Unlike Ghana, Mali was a Muslim kingdom since his foundation, and under it, the gold--salt trade continued . Other, less important trade goods were slaves, kola nuts from the south and slave beads and cowry shells from the north (for use as currency). It was under Mali that the great cities of the Niger bend--including Gao and Djenné--prospered, with Timbuktu in particular becoming known across Europe for its great wealth . Important trading centers in southern West Africa developed at the transitional zone between the forest and the savanna; examples include Begho and Bono Manso (in present - day Ghana) and Bondoukou (in present - day Côte d'Ivoire). Western trade routes continued to be important, with Ouadane, Oualata and Chinguetti being the major trade centres in what is now Mauritania, while the Tuareg towns of Assodé and later Agadez grew around a more easterly route in what is now Niger . </P> <P> The eastern trans - Saharan route led to the development of the long lived Kanem - Bornu empire as well as the Ghana, Mali, and Songhai empires, centred on the Lake Chad area . This trade route was somewhat less efficient and only rose to great prominence when there was turmoil in the west such as during the Almohad conquests . </P> <P> The Portuguese journeys around the West African coast opened up new avenues for trade between Europe and West Africa . By the early 16th century, European trading bases, the "Factories" established on the coast since 1445, and trade with the wealthier Europeans became of prime importance to West Africa . North Africa had declined in both political and economic importance, while the Saharan crossing remained long and treacherous . However, the major blow to trans - Saharan trade was the Battle of Tondibi of 1591--92 . Morocco sent troops across the Sahara and attacked Timbuktu, Gao and some other important trading centres, destroying buildings and property and exiling prominent citizens . This disruption to trade led to a dramatic decline in the importance of these cities and the resulting animosity reduced trade considerably . </P>

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