 From the 8th through the 15th century, black kingdoms of the western Sudan, such as Ghana, Mali, and Songhai, brought their political culture from the south.The divisive tendencies of the various groups within Mauritanian society have always worked against the development of Mauritanian unity.Both the Sanhadja Confederation, at its height from the 8th to the 10th century, and the Almoravid Empire, from the 11th to the 12th century, were weakened by internecine warfare, and both succumbed to further invasions from the Ghana Empire and the Almohad Empire, respectively.