Final answer:
The cities of Timbuktu, Djenné, and Gao were pivotal to West Africa as major trading hubs for gold and salt, centers of Islamic scholarship, and for their strategic control of regional economics and trans-Saharan trade networks.
Step-by-step explanation:
The cities of Timbuktu, Djenné, and Gao were historically significant in the region of West Africa primarily because they were major trading hubs for gold and salt. These cities flourished during the reign of the Mali and Songhai Empires, becoming centers of wealth and trade that connected West Africa with North Africa, the Middle East, and even Europe. Gold was the most prominent trade commodity, with West Africa supplying large quantities that ended up across the Old World, particularly affecting economies as far as the Middle East and Europe. Timbuktu and Djenné also became renowned as centers of Islamic scholarship and education.
Furthermore, these cities were strategically important for the control of the regional economy, as they linked the interior economies of West Africa with the trans-Saharan trade networks. Control of these cities allowed empires such as Mali and Songhai to levy taxes on trade commodities, further enriching their kingdoms. Additionally, the adoption of the same religion as many trans-Saharan traders strengthened ties between West African rulers and the merchant groups that traversed these routes.
In summary, Timbuktu, Djenné, and Gao were vital economic, educational, and religious centers during the medieval period of West African history, whose influence was felt across continents.