European countries colonized other lands in the 1500s due to lack of natural resources and overpopulation in Europe. This led to the colonization of the Americas by countries like England, France, Portugal, and Spain. However, the process resulted in the genocide and deaths of millions of Native Americans, as well as the enslavement of surviving Native Americans and the importation of African slaves to work in their place. Colonialism thus represented a horrific period in human history defined by death, slavery, and the replacement of indigenous populations with European colonizers.