How did west Africa create a large slave trade network?

Answer 1

The slave trade in West Africa has a long history, predating the arrival of the Europeans by centuries. Traditionally - and until the end of slavery in the 19th century - the procurers were the local African chiefs and kings, who either acquired slaves by taking prisoners of war, or by making raids into their neighbour's territories with the express purposes of catching people to sell as slaves.

Transport within Africa of slaves was often arranged by Arab slave-traders. Until the late 17th century, the Arab countries were also the major buyers/slaveholders. With the rise of sugar and cotton plantations in the Americas the Europeans became the biggest buyers and they established slave-collecting and transportation posts along the West African coast, encouraging traders and offering good prices. This of course was a powerful incentive to local kings and traders to step up their efforts.