European countries colonized other lands in the 1500s due to deforestation, poverty and overpopulation in Europe. By colonizing the Americas, European nations like England, France, Portugal and Spain gained new lands and opportunities for their people but committed genocide against Native Americans, killing millions. European colonists also brought African slaves to the Americas to work, especially after Native Americans proved to die easily in slavery conditions. The European colonization of the Americas was one of the bloodiest and most horrific times in human history.