henry the navigator started by paying portuguese sailors to explore the west coast of africa. in 1419 joao goncalves zarco discovered the madeira islands. later in the 15th century, vasco da gama reached the southwestern tip of africa and established the city of cape town, a portuguese colony. this opened the way to the indian ocean. in the next two centuries, the portuguese created a great trading empire on coasts of africa, the arabian peninsula, and india. the portuguese empire eventually weakened after the dutch east india company rose as the major power in indian ocean trade.