Igbo is a language of the Niger and Congo River basins, spoken by an estimated 25 million persons. Most live in Nigeria, and Igbo is one of Nigeria’s official languages. The Igbo people adopted an ideographic writing system of the neighboring Nsibidi until the Latin alphabet was introduced by European colonists. Igbo shows a wide degree of dialectical variation, but the development of a standard literary version of Igbo in 1972 (based on Owerri and Umuahia, the prestige dialects) has made Igbo more uniform among younger speakers.