How did the Ghana empire control trans-Saharan trade?

The Ghana Empire (fl. 7th–13th century) established itself as a powerful entrepot by acting as a strategic intermediary between northern salt traders and southern producers of gold and ivory. Its control over trans-Saharan trade was maintained through several key mechanisms:1

• Taxation: The king imposed import-export taxes on all goods entering or leaving the empire and levied a production tax on gold, which was the state's most valuable commodity.12
• Political Expansion: As the empire grew wealthy, it extended its political reach by absorbing lesser states and incorporating gold-producing regions to the south and key market cities to the north, such as Audaghost.1
• Military Power: The kings maintained a hierarchy of officials and a body of retainers who provided military force. This allowed them to enforce obedience from lesser groups and exact tribute, further consolidating their control over trade routes and resources.12
• Strategic Location: Situated between the Sahara and the headwaters of the Senegal and Niger rivers, the empire effectively funneled trade through its capital, where gold was exchanged for essential commodities like salt.12