The Nigerian-Biafran War (also known as the Nigerian Civil War) has left an indelible mark on the Igbo identity and has contributed to the current fractured state of the Igbo ethnic nationality. Prior to the Civil War, the peoples in what are now Abia, Ebonyi, Anambra, Delta (Aniocha, Oshimili, Ika, and Ndokwa areas), Imo, Enugu, and Rivers (Egbema, Ikwere, Ahoada, Obio-Akpo, Emuoha, Oyigbo, and Etche areas) states were all considered ethnically Igbo.
When Nigerian troops invaded Port-Harcourt and its environs in 1968 during the war, in order to avoid the mass brutalization and indiscriminate massacre which the Nigerians often unleashed in Igbo areas, the Ikwere (a sub-group of the Igbo ethnic nationality) and other Igbo-speaking peoples in what is now Rivers State denied any affiliation with the Igbo ethnic group and instead claimed to be separate ethnic groups of their own. This denial tactic was also employed by the Ukwuani and Ika peoples (Igbo-speaking peoples in what is now Delta State), and thus they were able to avoid the punitive measures the Nigerian government and military employed against other Igbo groups.
In the years following the war, there was a massive attempt to rewrite and erase any historical evidence that linked the Ikwere and Ika to the Igbo. In the 1979 Nigerian Constitution, Ikwere was officially recognized by the Nigerian government as a minority language separate from Igbo, despite being intelligible to certain Igbo dialects. In the state creation schemes of the post-war decades, Igbo-speaking areas were marginalized and were clustered into a disproportional number of states, placing them at a political and economic disadvantage that is still visible in today's Nigeria.