Final answer:
The rulers of Songhai converted to Islam, marking the beginning of the integration of commerce and religion in Songhay.
Step-by-step explanation:
The integration of commerce and religion in Songhay began with the conversion of the rulers of Songhai to Islam in the eleventh century. As a result of their contact with Muslim traders, the rulers were exposed to Islam and decided to convert. This conversion marked the beginning of the Gao imperial period and laid the foundation for the growth of Islam and the trans-Saharan trade in the region.