pearls and exported gold and slaves. Indeed, the growth of a vast empire by Arab-Muslim Jihads is not devoid of economic and political issues and brought in its wake the first real growth of the slave trade. This trade called the trans-Saharan slave trade provided North Africa and Saharan Africa with slave labor. The Tekrur were among the first converts to Islam, certainly before 1040. Two other major political entities were formed and grew during the 13th and 14th century: the Mali Empire and the Jolof Empire which become the vassal of the first in its heyday. Originating in the Mandinka invasion, Mali continued to expand, encompassing first eastern Senegal, and later almost all the present territory. Founded in the 14th century by the possibly mythical chief of the Wolof Ndiadiane Ndiaye, who was a Serer of Waalo (Ndiaye is originally a Serer surname which is also found among the Wolof). Djolof expanded its dominance of small chiefdoms south of the Senegal River (Waalo, Cayor, Baol, Sine – Saloum), bringing together all the Senegambia to which he gave religious and social unity: the "Grand Djolof" which collapsed in 1550. The Jolof Empire was founded by a voluntary confederacy of States; it was not an empire built on military conquest in spite of what the word "empire" implies. The Serer tradition of Sine attests that the Kingdom of Sine never paid tribute to Ndiadiane Ndiaye nor to any member of his descendants that ruled Djolof. Historian Sylviane Diouf states that "Each vassal kingdom—Walo, Takrur, Kayor, Baol, Sine, Salum, Wuli, and Niani—recognized the hegemony of Jolof and paid tribute." It went on to state that, Ndiadiane Ndiaye himself received his name from the mouth of Maissa Wali (the King of Sine). In the epics of Ndiadiane and Maissa Wali, it is well acknowledged that Maissa Wali was pivotal in the founding of this Empire. It was he who nominated Ndiadiane Ndiaye and called for the other states to join this confederacy, which they did, and the "empire" headed by Ndiadiane, who took residence at Djolof. It is for this reason scholars propose that the empire was more like a voluntary confederacy than an empire built on military conquest. The arrival of Europeans engendered autonomy of small kingdoms which were under the influence of Djolof. Less dependent on trans-Saharan trade with the new shipping lanes, they turn more readily to trade with the