Why did the atlantic slave trade from africa begin?

The  transatlantic slave trade . the  transatlantic slave trade began   in the 15th century, after the portuguese  started   exploring the coast of west  africa . at first the number of enslaved  africans   taken was small. she might have remained as a  slave   in  africa , he was eventually taken to the coast and sold to the europeans.

After the portuguese started exploring the coast of west africa. at first the number of enslaved africans taken was small. she might have remained as a slave in africa, he was eventually taken to the coast and sold to the europeans.