Perhaps because the linguistic divergence is very wide?

For those who say there no tribe call Edo you lie Edo is an ethnic group also call benins, I study Edo language in school in Benin we refer to ourselves as ovbiEdo meaning and and Edo child Benin is a nickname but Edo is our identity

mr1759:
For those who say there no tribe call Edo you lie Edo is an ethnic group also call benins, I study Edo language in school in Benin we refer to ourselves as ovbiEdo meaning and and Edo child Benin is a nickname but Edo is our identity

Edo history is pretty well orally told and retold and partly documented since the 15th century.

Benin people became known as Edo by 1440 AD when Oba Ewuare I ascended throne. By about 40 BC it was Igodo/Igodomigodo. It was also known as Idu Land. Igbo people still call Benin people Ndi Idu, for example.
When Prince Ginuwa left Benin in 1480 to form Warri as the first Ogiame, Edo as the new name would just have becoming more popular in regular use.
At some point between 40BC and 1440 AD, Benin became a common name and neighbouring chiefdoms/lands still mostly used that name. In the 1470s when the Portuguese first came, the coastal people they met told them of the powerful King of the whole area residing in Benin. Some early versions of Portuguese records call it Beny.

Fact is while the Core Benin people began using the world Edo as a tribal name, many allied lands and territories still used Benin mostly. The Empire was Benin Empire. Core Benin people were called Ivbiedo exclusively until 1991 when Edo State came into existence.
It is funny because Edo North and Edo Central actually have and had a bigger share in Benin Empire and name than Edo. Because they were warriors and had other key positions in imperial machinery of those days. Whereas Edo was virtually a tribal thing of core Benin people.

I cannot be sure, but it may be that traditional rulers in Edo North and Central played a role in it. May be they thought that if it is called Benin State, it could imply that it covers the domain of Oba of Benin. I may be wrong though. But what happened in Warri Province decades earlier may be a clue.

The same issue arose over 60 years ago in Warri. When Obafemi Awolowo as Premier of Western Region (Before Midwest Region was carved out by referendum in 1963) changed Olu of Itsekhiri title to Olu of Warri, other tribes protested because the area of Delta with Urhobo/Okpe, Itsekhiri, Ijaw and Isoko people was called Warri Province back then. Other tribes thought it would imply that Olu was overlord over all Warri Province of those days. The settlement was to rename the province as Delta Province.

AreaFada2:

Edo history is pretty well orally told and retold and partly documented since the 15th century.

Benin people became known as Edo by 1440 AD when Oba Ewuare I ascended throne. By about 40 BC it was Igodo/Igodomigodo. It was also known as Idu Land. Igbo people still call Benin people Ndi Idu, for example.
When Prince Ginuwa left Benin in 1480 to form Warri as the first Ogiame, Edo as the new name would just have becoming more popular in regular use.
At some point between 40BC and 1440 AD, Benin became a common name and neighbouring chiefdoms/lands still mostly used that name. in the 1470s when the Portuguese first came, the first coastal people they met told them of the powerful King of the whole area residing in Benin. Some early versions of Portuguese records call it Beny.

Fact is while the Core Benin people began using the world Edo as a tribal name, many allied lands and territiries still used Benin mostly. The Empire was Benin Empire. Core Benin people were called Ivbiedo exclusively until 1991 when Edo State came into existence.
It is funny because Edo North and Edo South actually have and had a bigger share in Benin Empire and name than Edo. Because they were warriors and had other key positions in imperial machinery of those those. Whereas Edo was virtually a tribal thing of core Benin people.

I cannot be sure, but it may be that traditional rulers in Edo North and Central played a role in it. May be they thought that if it is called Benin State, it could imply that it covers the domain of Oba of Benin. I may be wrong though. But what happened In Warri Province decades earlier may be a clue.

The same issue arose over 60 years ago in Warri. When Obafemi Awolowo as Premier of Western Region (Before Midwest Region was carved out by referendum in 1963) changed Olu of Itsekhiri title to Olu of Warri, other tribes protested because the area of Delta with Urhobo/Okpe, Itsekhiri, Ijaw and Isoko people was called Warri Province back then. Other tribes thought it would imply that Olu was overlord over all Warri Province of those days. The settlement was to rename the province to Delta Province.

Your write up are deep, indeed Benin is larger we need to come together in this Benin kingdom back then our grandfather will say as the Oba of Benin is powerful so is his brother the olu of warri over water, that what olu of warri title means in Benin ( Ogiamen king of water and so many other have their honor in Benin kingdom