The background is that the Dutch were fighting for their independence from Spain, which they did not formally secure until 1648. Portugal was at that time part of Spain, because of a dynastic alliance. So Dutch ships regularly attacked Portuguese ships, considering their cargoes spoils of war. Even after a truce was agreed in 1588 Dutch pirates continued to prey on Portuguese shipping. Some Dutch leaders thought this was a bad idea and tried to stop the pirates. Then in 1595 some English privateers captured a Portuguese ship returning from the Indies with so much spice, silk and other valuables that the amount of cash in the English treasury was doubled.
Both the English and the Dutch redoubled their efforts to explore the Indian Ocean and reach the riches of India, Indonesia, China, and Japan. The Dutch East India Company was founded in 1602 and sent its first expedition to India that same year. The Portuguese, used to monopolizing that trade, threatened to attack any Dutch ships they found in that region; the start of the war is usually dated to that Portuguese declaration. But it was the Dutch who attacked first, seizing a Portuguese galleon in February, 1603; the value of its cargo, including 1200 bales of Chinese silk, doubled the capital of the East India Company overnight. The war was on.
And what a war it was. Besides lasting 59 years, it included naval battles in the Sea of Japan, off Macau in China, off Goa and Kochi in India, off Malacca in Malaysia, off the Azores, and at Sao Tome in the Bight of Benin.
Land battles were fought in Brazil, Angola, South Africa, India, Sri Lanka, Malaysia, Sumatra, and Taiwan.