Answer:
The Almoravids envied the great wealth of Ghana, so they declared war on Ghana.
Step-by-step explanation:
The Almoravids were a North African people who came to power during the 11th century. This group of people were Arab Muslims, and they were interested in spreading Islam to neighbouring peoples. Moreover, the Almoravids envied the wealth that Ghana had gained due to the trans-Saharan trade. This led them to declare war on Ghana, until the Almoravids seized the city of Koumbi Saleh in 1076.