Established plantations on islands off the coast of africa.

The Portuguese were the first colonialists to establish sugar cane plantations on islands off the coast of Africa. The first cane plantations were established on the islands of Madiera and Sao Tomes. Sao Tomes was known as the largest sugar cane producer in the world and its economy grew to be one of the largest in the world
. Because sugar cane farming was and still is, a labor-intensive process,  the Portuguese began importing large numbers of African slaves to the island of Sao Tomes.