what caused west africans to transition from controlling the exchange of goods to european slave riders

There was an increase in demand for the slaves in the New World.

Explanation:

Historically, West Africa was producers of gold in the Middle Ages.  Portuguese became the first to exploit West Africa resources as they come across the gold in its region. European exchanged their products like cloth, utensils, weapons in return of gold, ivory, and stones. There was a transition from controlling the exchange of goods to European slave raiders. The West Africans became Europeans slave riders as they got rid of their enemies and received land, which was more wealth to them. Slavery was very much present in Africa before the arrival of Europeans. There was an increase in demand for slaves as the triangular trade was formed with the New World, Africa, and Europe. As European settlers began to settle in America, there was a demand for servent or worker for domestic help and in plantations.

answer: this is because archeologists keep finding artefacts and ancient ruins dated more than 10000 to 15000 years, date around scientists said humans discovered language; which is at least mysterious as scientists always have said that is necessary to have a language to have architecture and some basic maths.

explanation: brainlest

when world war i broke out across europe in 1914, president woodrow wilson proclaimed the united states would remain neutral, and many americans supported this policy of nonintervention. however, public opinion about neutrality started to change after the sinking of the british ocean liner lusitania by a german u-boat in 1915; almost 2,000 people perished, including 128 americans. along with news of the zimmerman telegram threatening an alliance between germany and mexico, wilson asked congress for a declaration of war against germany. the u.s. officially entered the conflict on april 6, 1917.