Spain has had a long and cloak and dagger foreign relationship history. Starting when the kingdoms of Aragon and Castile united under Isabella and Ferdinand, the foreign relationships were often through the catholic church of a battle field. Spain was largely protective and competitive with other nations for resources, wealth, and power. Spain wanted to avoid the Portuguese kingdom as much as it could while still trying to maneuvering itself to become the top dog on the Iberian Peninsula without starting all out war. Spain was however, not totally avoidant to war. In the beginning stages of Spanish unity, they conquered the bit of Ottoman Empire on the Iberian Peninsula called Granada. After conquering the province of Granada the campaign known as the Reconquista (re-conquest of Granada) came to cessation. Needless to say the Ottomans were not pleased with the Spanish for taking over one of their provinces, this would color the trading and diplomatic relationship with the Ottoman empire for decades to come, and was one of the major factors that lead to Ferdinand and Isabella exploring ways to Asia around the Ottomans. When Christopher Columbus came to the New World, he opened the door between the Spanish and the South American civilizations. Spain wanted the large quantities of gold and silver these civilizations had control over , and this coupled with the fact that the Native Americans weren't Christians made it possible and easy for Spain to convince conquistadores to travel to these civilizations and seize control, even over the largest and most powerful civilizations the Aztec and the Inca fell relatively quickly from the small but fierce Spanish conquistadores and soldiers. To avoid a war between Spain and Portugal over these new continents that Columbus had accidentally discovered on his way to India and Spain had mostly tamed, Spain looked to the Catholic church for help. Not wishing to see bloodshed from two firmly Christian kingdoms who supported his power, the Pope Alexander VI divided the world between Portugal and Spain known as the Treaty of Tordesillas. This treaty marked clear boundaries of where Spain and Portugal were allowed to colonize, while keeping well enough separated so that tensions didn't spark between them. With the exception of already established Christian kingdoms, there was no place these two civilizations covered. Portugal colonized Africa, Brazil, and the East Indies while Spain set up a much larger empire in the mines of South America, (excluding most of modern Brazil), Central America, Mexico, and the South Western United States. Due to the large amount of precious metals, the majority of the trading done by Spain in Europe was for goods of all kinds from all over Europe for the massive amounts of currency it had pumping in from the mines in New Spain. With the colonies producing Spain's food supply and possessing an already strong army, Spain had little reliance from other countries in Europe and mainly traded it's gold and silver to the poorer countries, albeit sparingly, to make itself more stable, centralized and powerful. Spain's foreign interactions were mainly caused by the empire's exploration for resources to make itself more powerful or the conquest of other civilizations to be able to have access to these resources and again make itself more powerful and secure in the world.