The Kon-Tiki Theory is a theory espoused by Norwegian writer Thor Heyerdahl about the way in which the islands of the Pacific were populated.
Accepted theory holds that the islands of the Pacific were populated from Asia. Heyerdahl, however, proposed that they were populated from South America. Moreover, he argued that the people who came from South America were actually Europeans. In order to prove that ancient migrations from South America to Polynesia were possible, Heyerdahl traveled on a simple balsa wood raft from South America to the Tuamotu Islands. The raft was named Kon-Tiki, after a name for an Inca god. This is where the name of the theory comes from.
While Heyerdahl did manage to prove that it was possible to travel from South America to Polynesia by primitive methods, modern DNA analysis has shown that people from South America did not colonize the Pacific.