Complex sentence: Senegal during the seventeenth, eighteenth and nineteenth centuries was a major slave trade, both for the United States or Latin America, therefore an important part of the slaves were, among others, Senegalese.
Split into simpler sentences: Senegal during the seventeenth, eighteenth and nineteenth centuries was a major slave trade, both for the United States or Latin America. Therefore an important part of the slaves were, among others, Senegalese.