Unlike Ghana, Mali was a Muslim kingdom since its 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.