The Kingdom of Dahomey formed from a mixture of ethnic groups on the Abomey plain. Historians theorize that the insecurity caused by slave trading may have contributed to mass migrations of groups to modern day Abomey, including some Aja, a Gbe people who are believed to have founded the city. Those Aja living in Abomey mingled with the local Fon people, also a Gbe people, creating a new ethnic group known as "Dahomey".
The Gbe peoples are said to be descendents of a number of migrants from Wyo. Gangnihessou (a member of an Aja dynasty that in the 16th century along with the Aja populace had come from Tado before settling and ruling separately in what is now Abomey, Allada, and Porto Novo) became the first ruler of the Dahomey Kingdom. Dahomey had a military culture aimed at securing and eventually expanding the borders of the small kingdom with its capital at modern day Abomey.
The Dahomey Kingdom was known for its culture and traditions. Young boys were often apprenticed to older soldiers, and taught the kingdom's military customs until they were old enough to join the army. Dahomey was also famous for instituting an elite female soldier corps, called Ahosi or "our mothers" in the Fongbe language, and known by many Europeans as the Dahomean Amazons. This emphasis on military preparation and achievement earned Dahomey the nickname of "black Sparta" from European observers and 19th century explorers like Sir Richard Burton.
The kings of Dahomey sold their war captives into transatlantic slavery; otherwise the captives would have been killed in a ceremony known as the Annual Customs. By c.1750, the King of Dahomey was earning an estimated £250,000 per year by selling Africans to the European slave-traders. Though the leaders of Dahomey appeared initially to resist the slave trade, it flourished in the region of Dahomey for almost three hundred years (beginning in 1472 with a trade agreement with Portuguese merchants), leading to
