Thanks to the scientific and technical knowledge that emerged at the end of the Middle Ages and to the political situation of the country and geographic position, Portugal becomes the main initiator of great geographic discoveries. During the first half of the 15th century, Henry the Navigator, Portuguese prince, sends out for more exploratory expeditions along the African western coast. He also establishes the school of navigation and cartography, in Sagres, which significantly helped the future Portuguese generations in exploring the Atlantic, and later the Indian Ocean. By the end of the 15th century the Portuguese sail by all of Africa and in 1498 they arrive in India. In the beginning of the 16th century, in the Indian Ocean, they founded Estado de India with its center in Goa, and took over the spice market. Thanks to the capable leaders of Estada da India, like Francisco Almeida and Alfonso Albuquerque, the Portuguese occupy almost all of the most important strategic points on the main commercial routes of the Indian Ocean. Due to a treaty in Zaragoza in 1529, the Portuguese in the East obtain the rights over the Maluku Islands, making it one of their main acquisitions because of the abundance of spice trade. In the middle of the 16th century, during its peak, the Portuguese colonial empire, stretches from Brazil all the way to China. In the beginning of the second half of the 16th century Portugal’s power slowly starts to diminish. In the year 1580 when Portugal tied itself to Spain through a union, it resulted in the involvement in several Spanish conflicts with several other European countries, which would greatly harm the Portuguese economy. In the beginning of the 17th century the Dutch and the English occupied numerous Portuguese colonies in the Indian Ocean and gained dominance over the spice trade.