The chief town and traditional capital of the area was the town of Kétou (Kétu), which is considered to be one of the oldest capitals of the Yoruba-speaking people, tracing its establishment to a settlement founded by a descendant of Oduduwa (also known as; Odùduwà, Oòduà and Eleduwa) called Sopasan or Soipasan.
The Oba of the town were traditionally styled "Alákétu", and are related directly to Ile-Ife in present-day Nigeria.
Other towns that were historically part of the Kétu Kingdom are; Ketu is one of the sixteen original kingdoms established by the children of Oduduwa in Oyo mythic history, though this ancient pedigree has been somewhat neglected in contemporary Yoruba historical research, which tends to focus on communities within Nigeria.
In any case, there is no doubt that Ketu and Oyo maintained friendly relations largely due to their historical, linguistic, cultural and ethnic ties.
It is believed that the inhabitants (or at least some) of Ketu originally belonged to the Oyo people of Nigeria and were pressed westward by a series of wars between the 12th and the 15th centuries.