When, therefore, a demand for workmen arose in America, European exportation was limited by religious ties and economic stability. African exportation was encouraged not simply by the Christian attitude toward heathen, but also by the Moslem enmity toward the unconverted Negroes. Two great modern religions, therefore, agreed at least in the policy of enslaving heathen blacks, while the overthrow of black Askias by the Moors at Tenkadibou brought that economic chaos among the advanced Negro peoples and movement among the more barbarous tribes which proved of prime advantage to the development of a systematic trade in men. The modern slave trade began with the Mohammedan conquests in Africa, when heathen Negroes were seized to supply the harems, and as soldiers and servants. They were bought from the masters and seized in war, until the growing wealth and luxury of the conquerors demanded larger numbers. Then Negroes from the Egyptian Sudan, Abyssinia, and Zanzibar began to pass into Arabia, Persia, and India in increased numbers. As Negro kingdoms and tribes rose to power they found the slave trade lucrative and natural, since the raids in which slaves were captured were ordinary inter-tribal wars. It was not until the eighteenth and nineteenth centuries that the demand for slaves in Christian lands made slaves the object, and not the incident, of African wars. In Mohammedan countries there were gleams of hope in slavery. In fiction and in truth the black slave had a chance. Once converted to Islam, he became a brother to the best, and the brotherhood of the faith was not the sort of idle lie that Christian slave masters made it. In Arabia black leaders arose like Antar; in India black slaves carved out principalities where their descendants still rule.