Oyo Mesi

Led by the Bashorun (or hereditary "Prime Minister"), the Oyo Mesi were also expected to serve as a check on the despotic authority of each individual emperor that they crowned.

In the event of any given reign having descended into tyranny, the Bashorun - after having put the matter to a vote in the Oyo Mesi previously - was expected to perform a traditional rite during which he would bring a calabash (which was to be either empty or laden with the eggs of a parrot) and present it to his monarch.

These wide powers that the Oyo Mesi had were checked in turn by the Ogboni, a subordinate council of noble elders that were sworn to the service of the Earth goddess.

This organizational structure survived the fall of the old empire during the Yoruba civil war in the 19th century, and exists now in the ceremonial monarchy of contemporary Oyo.

Each has his own inalienable functions in the realm (although many of these responsibilities - such as the Samu's needing to commit ritual suicide - are now dormant), and all are collectively the Oyo equivalent of the Iwarefa in other Yoruba kingdoms: