Portugal was literally first European country to start Age of Exploration, the pioneer. It started in the 1400s actually. Why do you think it's Portuguese Emblema on Shogun 2 TW on "European traders"? Why was first European-Japanese dictionary ever made a Portuguese-Japanese one done by said Portuguese explorers? Why is Black Ship in Shogun 2 basically a replica of the typical Portuguese Carrack of the time?
On Exploration then came Spain (decades after Portugal had started), then the Dutch and the English. Last 2 ones benefited more since maps and sea routes already defined, less riskier to make business.
Any exploration age game without Portugal in the list will be doomed to be incomplete.
Portugal explored towards the Orient, while changing Silk Route price dynamics (most expensive tradeable goods of the time) and making Silk Route goods go through Portuguese Ships instead.
Spain headed towards the Western Americas. Spain brought so much Gold it actually started inflating highly in value, having several bankrupcies, difficulty in paying mercenaries which then led to a defeat against Netherlands.
There were also some big fights between Portuguese Empire versus Ottoman Empire in dispute of Indian Ocean. Even Venetians lended their sea fleet to help the (!) Ottomans because Portuguese route through South Africa was making Venice lose money.
There's so much potential.
To be put as DLC?
So much History and potential for a game in such timeframe. From 1400s to 1580, the exploration ride never ends.Spoiler Alert, click show to read: