It was the people that told the slave traders and the Colonialists who they were. And the slavers/colonialists acted accordingly
*Within themselves ( the Igbo and olu)were those delineations you write about, but outside in strange land, they knew themselves as Igbo.
*In faraway Jamaica in the 16th century, they told their enslavers they were called Igbo. *Those slavers dubbed them red Eboes on account of their skin color.
There were no mistakes about their identity in the midst of a host of other slaves captured from West Africa.
*Amongst them are greetings that point at their identity - Igbo wu Igbo ekeleem unu, Igbo kwenu, Igbo ndewonu, Kelee Igbo, Kelee Olu, maka na Igbo na olu bu ofu.
Amongst them were names extracted from their essence. Igbo as a prefix existed as as people; Igbozuruike, Igboanugo, Igbojekwu, Igboariam, Igbonta Igboukwu, Igbo eze, Igboetiti, Igbonoba, Igbo uzo, Igbonodu, Igbodo...
And as suffix: Abigbo (Mbaise dance), Ama Igbo, RumuIgbo, Obigbo, Egelege Igbo (Igbo traditional wrestling) Mgborogwu Igbo ( Igbo native medicine) etc.
*In folklore takes were references to Igbo. Ogirisi Igbo mara mma n'Igbo
*In faraway US were slave rebellions by Igbos.
In Haiti and in US the landings, the mass suicides...
And as for the language, they clearly were Igbo but with diversified dialects which needed needed synchronization. That's how Union Igbo autography came forth though admittedly, at the behest of the Colonial Lords...
Ikwerre chiefs never objected in the early 1900s to being classified as Igbo.
At the Willinks Commission too, they did not raise objections.
Let us place these things as objectively and as truthfully as possible good brothers!