The Conquest
I n 1492, the world changed forever. This was the Age of Discovery. 
Made possible by vast improvements in navigational techonology, Europeans set sail to discover new trade routes. In the early 15th century, Portugese explorers began to traverse treacherous waters in an effort to circumnaviagte the globe. In 1487, Bartholomeu Dias succeeded in sailing around the southern tip of Africa.
Europeans especially wanted an all-water route to India. Christopher Columbus, a native of Genoa, Italy, believing that the world was round, thought he could most easily reach India by sailing west, not east. 
Columbus took his idea to Spain's Queen Isabella I. Columbus' appeal to Isabella to finance his planned voyage to the East by sailing west was originally turned down. Then she suddenly changed her mind. As a result, Spain gained a New World.
It was, of course, a world already inhabitaed by people, whom Columbus called Indians. The first contact between Columbus's crew and the natives was not a meeting of equals. It was a European conquest of the Indians, by both direct and indirect means. Although Europeans slaughtered countless numbers of Indians, the indirect methods claimed many more Native lives. The most deadly of these indirect methods was the passage of disease from Europeans to Indians without any natural immunities.