Vasco De Gama, The 15th Century Mariner

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Vasco de Gama is representing the Portuguese exploration. A couple of things about Portugal in the 15th century.
1. It was resource poor.
2. It had a fair bit of coast line.
This meant that Portugal relied upon trade to grow.
Also the Iberian peninsula was the only place in Europe where Muslims can be found in large numbers in the 15th century, which meant that the Christian Crusading spirit was quite strong there, presumably because Muslims had brought so much stability and prosperity to the region.The chief among these would-be crusaders  was prince Henry the Navigator. And all that knowledge gave Portuguese sailors a huge competitive advantage when it came to exploration.
He was, however, a patron  not only of sailors themselves, but of a special school at Sagres  in which nautical knowledge was collected and new maps were made and all kinds of awesome stuff happened.
Henry commissioned sailors to search for two things. First a path to the Indian ocean so that they could get in on the lucrative spice trade, and second to find the kingdom of Prestor John, a mythical Christian king who was supposed to live in Africa somewhere, so that he could have the help of Prestor Johnn in the crusade.
The Gama was the king Henry's protegese to make it around Africa and into the Indian Ocean. In 1498, he landed at Calicut, a major trading center on India's West coast. And when he got there merchants asked him what he was looking for.
He answered with three words: Goald and Christians, which basically sups up Portugal's reasons for exploration.
So once the Portugese bridged the Indian Ocean, they didn't create like huge colonies, because they were already powerful empires in the region. apparently they sat in the middle of the Indian Ocean doing nothing. Actually they were able to capture and control a number of coastal cities, creating what historians call a "trading post empire". They could do this thanks to their armed ships, which captured cities by firing cannons into city walls like IRL Angry Birds.
So since the Portuguese didn't have enough people or boats to run the Indian Ocean trade, they had to rely on extortion. So Portuguese merchant ships would capture other ships and force them to purchase a permit to trade called a cartaz and without the cartaz, a merchant could not trade in any of the towns Portugal controlled. To merchants who sailed the Indian Ocean for years in relative freedom the Portugese were just glorified pirates, extracting value from trade without adding to its efficiency or volume. So the Cartaz strategy worked for a while, but Portugal never really took control over the Indian Ocean trade. They were successful enough that their neighbors Spain, became interested in their own route to the Indies.