Final answer:
Trade helped Ghana develop by accumulating wealth through the control of trans-Saharan trade, which was key in the expansion of Ghana's city-states into powerful empires.
Step-by-step explanation:
Trade significantly contributed to the development of Ghana by facilitating wealth accumulation. The Ghana Empire controlled trans-Saharan trade, which included the lucrative exchange of gold and salt. This trade route became more established as demand for gold increased, with Arab merchants buying sub-Saharan gold. In the eleventh century, this trade was substantial enough to influence commerce in the Mediterranean, leading to West African gold being used to mint European coins. This wealth enabled the growth of city-states into kingdoms and empires, and the power acquired through trade helped political leaders to raise armies and participate in complex systems of alliances and diplomacy. As trade taxed by empire contributed to rich kingdoms, it fostered economic development, rather than cultural isolation, economic stagnation, or technological backwardness.