The African empires of Ghana, Mali, Songhai, Hausa, Kanem-Bornu and others rose to power through the might of their horse-borne warriors and their ability to control the trans-Saharan trade routes and those along the the Rivers Niger and Volta. The trade routes also supplied the larger North African horses which replaced the smaller native breeds. In the first half of the second millennium AD these empires were converted to Islam and numerous jihads or Holy Wars were fought to establish or maintain Islamic belief in regions considered pagan. Captives of war were traded for horses and weapons. The horse remains today a powerful image in the arts of Sudanic peoples, though whether it is regarded as a symbol of power or oppression is dependent on historical associations. Many communities in the Sahel regions share common ancestral myths in which horses and riders figure prominently. Among the Senufo peoples equestrian figures are found in shrines of religious practitioners or diviners. They are symbols of wealth, prestige and power. Other objects placed in shrines include animal motifs, rings and other amulets which are regarded as belonging to the world of bush spirits. The horse and rider is a dominant figure and considered a strong, fast and aggressive leader of the spirits. Islamic amulets may be worn around the neck of the horseman for protection against evil spirits. Although the Senufo had historical experiences of Islam, during the late nineteenth century Muslim crusaders led by Samory threatened their traditional way of life. This figure wears protective Islamic armlets around his neck, holds a gun in his right hand and is therefore strongly associated with the power of the invading Muslim horsemen from the north.