Formation
South America broke off from the west of the supercontinent Gondwanaland around 135 million years ago (Ma), forming its own continent. Starting around 15 Ma, the collision of the Caribbean Plate and the Pacific Plate resulted in a series of volcanoes along the border that created a number of islands. The gaps in the archipelago of Central America filled in with material eroded off North America and South America, plus new land created by continued volcanism. By 3 Ma, the continents of North America and South America were linked by the Isthmus of Panama, thereby forming the single landmass of the Americas.
Settlement
Archaeological finds establish the widespread presence of the Clovis culture in North America and South America around 10000 BC. Whether this is the first migration of humans into North America and South America is disputed, with alternative theories holding that humans arrived in North America and South America as early as 40000 BC.
The Inuit migrated into the Arctic section of North America in another wave of migration, arriving around 1000 CE. Around the same time as the Inuit migrated into North America, Viking settlers began arriving in Greenland in 982 and Vinland shortly thereafter. The Viking settlers quickly abandoned Vinland, and disappeared from Greenland by 1500.
Large-scale European colonization of the Americas began shortly after the voyages of Christopher Columbus in 1492. The spread of new diseases brought by Europeans and Africans killed most of the inhabitants of North America and South America, with a general population crash of Native Americans occurring in the mid-sixteenth century, often well ahead of European contact. Native peoples and European colonizers came into widespread conflict, resulting in what David Stannard has called a genocide of the indigenous populations. Early European immigrants were often part of state-sponsored attempts to found colonies in the Americas. Migration continued as people moved to the Americas fleeing religious persecution or seeking economic opportunities. Many individuals were forcibly transported to the Americas as slaves, prisoners or indentured servants.