Conquistadors such as Pizarro and Cortes respectively took the land of the Incas and the Aztecs, brutally killing them off with their more sophisticated weaponry and using the remaining people to mine gold or silver, to be slaves so that the powerful monarchy Spain could become wealthier, and, with dominion over people and their land and having more money with which to exert their influence in Europe and the rest of the world, become stronger and oppress their colonies in the New World. Spain made an empire by oppressing the native peoples of the land they conquered, taking easily the nations of people who couldn’t adequately defend themselves against the technologically -advanced Spain. They gained wealth and power, becoming the most powerful nation in Europe, ensuring the protection of their massive amount of power and money. This was further insured by the Treaty of Tordesillas, allowing Spain the New World and protecting the vast amounts of wealth from Portugal.
For effects and such, see: Columbus sails the Ocean Blue