<P> During the LGM the Laurentide Ice Sheet covered most of northern North America while Beringia connected Siberia to Alaska . In 1973 late U.S. geoscientist Paul S. Martin proposed a "blitzkrieg" colonization of America by which Clovis hunters migrated into North America around 13,000 years ago in a single wave through an ice - free corridor in the ice sheet and "spread southward explosively, briefly attaining a density sufficiently large to overkill much of their prey ." Others later proposed a "three - wave" migration over the Bering Land Bridge . These hypotheses remained the long - held view regarding the settlement of the Americas, a view challenged by more recent archaeological discoveries: the oldest archaeological sites in the Americas have been found in South America; sites in north - east Siberia report virtually no human presence there during the LGM; and most Clovis artefacts have been found in eastern North America along the Atlantic coast . Furthermore, colonisation models based on mtDNA, yDNA, and atDNA data respectively support neither the "blitzkrieg" nor the "three - wave" hypotheses but they also deliver mutually ambiguous results . Contradictory data from archaeology and genetics will most likely deliver future hypotheses that will, eventually, confirm each other . A proposed route across the Pacific to South America could explain early South American finds and another hypothesis proposes a northern path, through the Canadian Arctic and down the North American Atlantic coast . Early settlements across the Atlantic have been suggested by alternative theories, ranging from purely hypothetical to mostly disputed, including the Solutrean hypothesis and some of the Pre-Columbian trans - oceanic contact theories . </P> <P> The Norse settlement of the Faroe Islands and Iceland began during the 9th and 10th centuries . A settlement on Greenland was established before 1000 CE, but contact with it was lost in 1409 and it was finally abandoned during the early Little Ice Age . This setback was caused by a range of factors: an unsustainable economy resulted in erosion and denudation, while conflicts with the local Inuit resulted in the failure to adapt their Arctic technologies; a colder climate resulted in starvation; and the colony got economically marginalized as the Great Plague and Barbary pirates harvested its victims on Iceland in the 15th century . Iceland was initially settled 865--930 CE following a warm period when winter temperatures hovered around 2 ° C (36 ° F) which made farming favorable at high latitudes . This did not last, however, and temperatures quickly dropped; at 1080 CE summer temperatures had reached a maximum of 5 ° C (41 ° F). The Landnámabók (Book of Settlement) records disastrous famines during the first century of settlement--"men ate foxes and ravens" and "the old and helpless were killed and thrown over cliffs"--and by the early 1200s hay had to be abandoned for short - season crops such as barley . </P> <P> Christopher Columbus discovered the Americas in 1492 under Spanish flag . Six years later Vasco da Gama reached India under Portuguese flag, by navigating south around the Cape of Good Hope, thus proving that the Atlantic and Indian Oceans are connected . In 1500, in his voyage to India following Vasco da Gama, Pedro Alvares Cabral reached Brazil, taken by the currents of the South Atlantic Gyre . Following these explorations, Spain and Portugal quickly conquered and colonized large territories in the New World and forced the Native American population into slavery in order to explore the vast quantities of silver and gold they found . Spain and Portugal monopolized this trade in order to keep other European nations out, but conflicting interests nevertheless led to a series of Spanish - Portuguese wars . A peace treaty mediated by the Pope divided the conquered territories into Spanish and Portuguese sectors while keeping other colonial powers away . England, France, and the Dutch Republic enviously watched the Spanish and Portuguese wealth grow and allied themselves with pirates such as Henry Mainwaring and Alexandre Exquemelin . They could explore the convoys leaving America because prevailing winds and currents made the transport of heavy metals slow and predictable . </P> <P> In the American colonies depredation, disease, and slavery quickly reduced the indigenous American population to the extent that the Atlantic slave trade had to be introduced to replace them--a trade that became norm and an integral part of the colonization . Between the 15th century and 1888, when Brazil became the last part of America to end slave trade, an estimated ten million Africans were exported as slaves, most of them destined for agricultural labour . The slave trade was officially abolished in the British Empire and the United States in 1808, and slavery itself was abolished in the British Empire in 1838 and in the U.S. in 1865 after the Civil War . </P>

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