There were many changes that happened in Africa over this time that can be traced to the Trans-Saharan trade. This trade was largely between West Africa and North Africa and involved gold and slaves and salt.
Perhpas the most important change that happened during this time was that the people of West Africa were exposed to Islam through trade. Islam, of course, began in the 600s CE and eventually reached North Africa. Muslims came to dominate the trade with the West African states. This led to the conversion of many West Africans. For example, the Kingdom of Mali was largely Muslim and its king, Mansa Musa, made a famous pilgrimage to Mecca in the 1300s.
In this way, the Trans-Saharan trade changed the culture of West Africa tremendously by introducing Islam.