Can you explain why please?
I'll even add on to what others said.
Basically.....there are a ton of ethnic groups in Nigeria but Hausa, Yoruba and Igbo are the largest.
Hausa are mostly Muslim, historically very autocratic and didn't believe in education for women.
Igbo were very democratic and felt everyone should debate and give opinions to figure how to solve problems...more equality.
Yoruba are sorta traditional like Hausa but more open minded like Igbo.
The British felt that the Hausa's autocratic style and tendency to be less educated overall would make them easier to work with as leaders.....so the Hausa ended up with a ton of power during colonialism and even right when the Brits left. The northern part of Nigeria where the Hausa traditionally resided is quite a bit larger than the southwest (Yoruba) or southeast (Igbo).
However....the oil and wealth was in the southern parts, especially in Igboland. The Igbos wanted more influence and power since Nigeria's best monetary assets were near them. Plus they simply didn't like a top heavy government approach. Eventually they go to war....Biafran War, from 1967 to 1970. Igbo, with more money and support may have had a shot but the Hausa with some Yoruba help ended up winning.
I'm not sure Nigeria has even had an Igbo president since inception.
There's probably a lot more to the beef but that's what I know.