A Yoruba oba is a sacred office. At installation the candidate undergoes rites that separate him from ordinary humanity — in some traditions including seclusion, the consumption of specific substances, and contact with the regalia of predecessors — after which he is addressed as kabiyesi, a term implying that no one may question him, is not to be seen eating, and performs annual rites that no one else may perform. The Ooni of Ife and the Alaafin of Oyo hold the senior thrones, and their relative precedence has been disputed for centuries on the basis of competing creation and migration accounts. Under colonial and then Nigerian federal government the political authority of obas was progressively reduced to the ceremonial and advisory, but the ritual office was not abolished and continues; recent Oonis and Alaafins have been Christians or Muslims by personal confession while continuing to perform the traditional rites, an arrangement Nigerians find unremarkable and outside observers find puzzling.