The Spanish Empire had what is considered its Golden Age during the 16th and 17th centuries, during which time Spain controlled an extraordinary amount of territory in Europe and Asia, and began to colonize the Americas as well. At the same time, Portugal had increased its Independence and its own territories, claiming Brazil and discovering Australia.
At the time, both countries were expanding their territories. Spain's most important expansion was the Castilian Empire in America, where mass deposits of silver were found in Mexico, causing their economic worth to soar. Portugal held similar interests in South America, so their paths did not cross except for trade, and Portuguese ships continued to explore, being the strongest factor in the Age of Discovery. Spain, meanwhile, completed the first full circumnavigation of the globe in 1522. These expansions opened up new lands and trade routes for Europe and Asia, as well as making the routes between Europe and the Americas safer and more common. However, near the end of the 16th century, the last Kings of Portugal died without heir, and King Phillip II claimed Portugal for Spain. Spanish rule over Portugal lasted until the 1640 revolt led by John IV.