True. Buying on margin. Economy people were making some serious money. Farms were doing great, until late 1920's.
Income money that's the right answer.
The main factor that contributed to the rising of the Kingdom of Ghana is the African trade in gold and salt. Though the resources did not come from Ghana, it was situated in a trading route between salt miners in North Africa and gold traders from South Africa.
The main way in which domesticating livestock allowed civilizations to spread is that people were freed up to do other things like woodworking and opening shops, since they no longer needed to hunt and gather their food and resources.
