The migration of the Bantu people began around 1500 B.C.E., and by 1000 C.E. the Bantu occupied most of sub-Saharan Africa. The migration is believed to be due to overpopulation stretching resources in the Bantu homeland in modern-day Nigeria. As a result, groups of people gradually began to leave to set up new agricultural settlements. The Bantu people often intermarried with those they came in contact with, and these people often adopted the Bantu language and joined the Bantu society.
Around 1000 B.C.E. the Bantus began to produce iron tools, which enabled them to clear more land and expand agriculture. This led to an increase in both population and migration. The overall population of Africa grew from 3.5 million in 400 B.C.E. to 22 million in 1000 C.E.. Around 500 C.E. the cultivation of bananas—which had made their way to Africa via the Indian Ocean trade—enabled the Bantus to expand into heavily forested regions and to continue migrating. Today there are over 500 distinct (though related) languages that can be traced back to the Bantus.
Humans migrated to New Guinea and Australia around 45,000 years ago via watercraft. These people developed maritime technology and agricultural expertise, and eventually established settlements on Pacific islands. Beginning around 1600 B.C.E., the movements that settled the Polynesian islands migrated to surrounding islands including Vanuatu, Fiji, Samoa, and much later, Hawaii. Long-distance voyages were taken using double canoes with large triangular sails, which carried a platform between the two hulls for shelter. Some scholars believe that the settlement was accidentally caused by sailors being blown off course, while others believe it was a planned colonization. As the migration spread, so did the cultivation of new food crops such as yams, taros, breadfruit, and bananas, as well as the introduction of domesticated animals such as dogs, pigs, and chickens.
The Polynesian islands developed into hierarchical chiefdoms in which leadership was passed down to the eldest son, and relatives served as the local aristocracy. Conflict between groups, as well as population pressure, often led to further migration to new areas. The cultures and languages of these widely dispersed islands often adapted and evolved differently.