*"I challenge you to prove to me that idu is Benin."
"what was the real name of Benin kingdom? And when did obaship started in Benin Kingdom?" - - _Ika Man

If you do not know that Idu is Benin, it shows you do not follow your history. As an Ika man, if you are from Agbor or Asaba, you should know the people referred to as Oyin'idu. Oyin'idu are the Benin or Ẹdo people.
The name of people kept on changing from one time to another without divorcing themselves from the common ancestral identity of Idu (Erinmwin'idu).

From Idu (dwelling) which is the name of the primogenitor "Idu" to Ubini (Land of multitude or inexhaustible), and to Ẹdo (be doing favorably), it had remained one people, and not one invading the other.
The Ika people were part of them, but leaving those behind, they called them Oyin'idu (main people of Idu). A lineage of Idu is the Akka or Aka which became the name that Urhobo or Isoko associated with the Benin as "Aka."

While the Itsekiri associated Benin with the name Ubini as at the time they migrated. It was this Ubini which was colloquially referring to as Bini, that the Portuguese met and pronounced as Benin.
Meanwhile, during the reign of Ọba Ẹwuare I, he made Ẹdo his friend's name as the name of the people, as honour to Ẹdo for saving his life from the ambush of his master, Ogiefa.

So since then Ẹdo and Benin is used simultaneously. While Ẹdo is language and people, Benin is the Kingdom and the name of the ancient kingdom empire, and as well as the name of the city or people.
The name Benin became an internatiaonal name which was used during the period of four centuries bilateral trade with the Portuguese before the partitioning of Africa to the colonial masters.

Thereafter, the slave trade began in other lands except in Benin Kingdom, and colonization before the amalgamation of North and South territories to become Nigeria in 1914 for the colonial administration.

Before the advent of the colonial masters, Idu land Igodomigodo, was ruled by 31 Ogiso, under the Ogiso dynasty till about 1100AD, and by the 11th - 12th Century the Ọba dynasty started as a continuity of the monarchy after the break or interregnum that brought in a regent administrator, of Evian who wanted to make his son Irebor the Ogiamiẹn as hereditary, but the people revolted, having unravel the whereabouts of the exiled prince Ekaladerhan Izoduwa (as Oduduwa in Ife).

As he could not return at Oldage sent Oranmiyan. The same King makers in case of administrator, but properly constituted as King Installers as for hereditary, called the Uzama, installed Oranmiyan as Ọba, as the name of Ogiso had been violated by the default of interregnum.

From then the Ọba dynasty began to date with the 40th Ọba, Ọba Ẹwuare II, N'Ogidigan. The continuity of Benin monarchy is enshrined in the duty of the Uzama (The Ediọn of Benin Kingdom) of which the Heir- Apparent was later included during the time of Ọba Ẹwuare I, Ogidigan, The Great. The Kingdom of Benin is called "Ẹguae" throughout the dynasties. Ẹguae ẹmwẹ sẹ!