The Songhai had settled on both banks of the middle Niger River. They established a state in the 15th century, which uni a brilliant civilisation [...] The capital was at Gao, a city surrounded by a wall. It was a great cosmopolitan marketplace
precious woods were traded in exchange for salt, cloth, arms, horses and copper. [...]
Based on the excerpt above, what characteristics did the Songhai kingdom have that contributed to the success of all African Kingdoms ?
Strong infrastructure and tax revenue

Access to major bodies of water for trade
O Enough natural resources to remain self-sufficient
A reliance on slave labor for production and protection