"Little is known about the history of N Benin. In the south, according to oral tradition, a group of Aja migrated (12th or 13th cent.) eastward from Tado on the Mono River and founded the village of Allada. Later, Allada became the capital of Great Ardra a state whose kings ruled with the consent of the elders of the people. Great Ardra reached the peak of its power in the 16th and early 17th cent.
A dispute (c.1625) among three brothers over who should be king resulted in one brother, Kokpon, retaining Great Ardra. Another brother, Do-Aklin, founded the town of Abomey, and the third, Te-Agdanlin, founded the town of Ajatche or Little Ardra (called Porto-Novo by the Portuguese merchants who traded there). The Aja living at Abomey organized into a strongly centralized kingdom with a standing army and gradually mixed with the local people, thus forming the Fon, or Dahomey, ethnic group.
By the late 17th cent. the Dahomey were raiding their neighbors for slaves, who were then sold (through coastal middlemen) to European traders. By 1700, about 20,000 slaves were being transported annually, especially from Great Ardra and Ouidah, located on what was called the Slave Coast. In order to establish direct contact with the European traders, King Agaja of Dahomey (reigned 1708-32), who began the practice of using women as soldiers, conquered most of the south (except Porto-Novo). This expansion brought Dahomey into conflict with the powerful Yoruba kingdom of Oyo, which captured Abomey in 1738 and forced Dahomey to pay an annual tribute until 1818. However, until well into the 19th cent. Dahomey continued to expand northward and to sell slaves, despite efforts by Great Britain to end the trade."
From the above can we conclude that the Ardras are really the Ajas, the Dahomeans are Fon or Foin, the Abos are of Abomey and the Ayois are really from the Yoruba City of Oyo? These can include both Yorubas from the City of Oyo, as well as other tribes/nations, all depending on the chronology of when the Yorubas were expansionist or vanquished. We see also that there was Great Ardra and Little Ardra. That the Ajas of North Benin were the origins the Ardras, and the Fon/Foin of Abomey which later became Dahomey and the Dahomeans."