Before Hausa man or people came to Nigeria, many other tribes were in Nigeria. In fact, the father of Hausa people even married from Katsina but today, we are told that his children founded Kano, Katsina, Zamfara, Kaduna, Bauchi, and others. How about other tribes in the area before AD? All ran and hid under Hausa been given a major tribe status now. Without saying you are Hausa, admission, some works and even activities in the area , you can't take part. Same thing happened in Yoruba land of today. Southwest had original Ugbo people, Benin, Nupe, Ijebu, Itsekiri, Igala, Egba, Oduduwas before the new name Yoruba (Yariba) was introduced. But as soon as Ajayi made the British to declare it a major tribe, all other tribes abandoned their names in order to excel in politics, gain employment, access scholarship and even become popular. That is why there is no particular King in Yoruba as over 5 rulers claim to be King.
In southeast, there were Olu and Igbo. Olu people are Igala people and mostly found around the river sides. There are others like Aro and Eris who are jointly called Igbo. But when the government adopted Igbo as the major tribe, the Olu people had to drop the name in order to gain admission to school, secure jobs, be actively involved in politics, etc. Do you know that Tafawa Balewa or Aminu Kano was not Hausa? Do you know that Nnamdi Azikiwe and Alex Ekwueme were not Igbo but Benin and Igala?
The corruption of today started with the fraud arrangement of favouring the new people at the expense of the original people. Tomorrow, if another new tribe is adopted in Southeast, Southwest and North, the names of the major tribes we have today will fade away in 3 months.
So, do not think that everyone in East is Igbo or west is Yoruba or North is Hausa.