Spain and Portugal led the ocean-going European explorers of the 15th and 16th centuries. Portuguese ships travelled to the southern Atlantic and the African coast while Columbus headed west in Spanish ships in 1492 to find a path to the trade centres of Asia.
The Spanish and Portuguese looked to the Pope, head of the Roman Catholic Church, to legitimate their claims as they expanded their reach. In 1481, a Papal Bull, a special charter, granted the Canary Islands to the Castilians of Spain and rights to Africa for the Portuguese.
When it was revealed that lands lay across the Atlantic (Europeans would soon realize these were the expansive continents of North and South America), disputes arose as to who had rights to these territories. The Treaty of Tordesillas in 1494 split the “New World” between Spain and Portugal. Although very little of the new lands had been seen, lines were slashed across the globe, giving most of North and South America to Spain and the easternmost area of what is now Brazil to Portugal. The Treaty was sanctioned by a Papal decree, but future bulls moved this meridian back and forth, giving Spain control in Asia and allowing Portuguese expansion in Brazil. The French and the British were restricted from those areas under Papal authority, but they soon disregarded the bulls. Those nations not under the Treaty launched the search for a Northwest Passage, or engaged in piracy, conflict, and trade monopolies in other areas.The impact of the Treaty of Tordesillas on the Pacific Northwest came centuries later. The Spanish had settlements in Mexico and California, but had not expanded north into the colder regions of the northern Pacific. By the 18th century, the Portuguese were no longer leaders in exploration, but the Russians, British, and French were sending expeditions that threatened what the Spanish still believed to be their rightful territory, granted by the Pope. Spain finally sent vessels to the Pacific Northwest, to areas they had all but ignored for more than 275 years.