of Dyarim. Hausa, as well as other Afroasiatic languages such as Kanuri, Margi, Karai-Karai and Bade (another West Chadic language spoken in northeastern Nigeria), have historically been written in a modified Arabic script known as ajami. However the modern official orthography is now a romanization known as boko introduced by the British regime in the 1930s. The major native languages, in terms of population, are Hausa (over 80 million when including second-language, or L2, speakers), Yoruba (over 50 million including L2 speakers), Igbo (over 30 million, including L2 speakers) Fulfulde (13 million), Efik-Ibibio cluster (10 million), Kanuri (8 million), Tiv (5 million), Nupe (3 million) and approx. 2 to 3 million each of Karai-Karai Kupa, Kakanda, Edo, Igala, Idoma and Izon. Nigeria's linguistic diversity is a microcosm of much of Africa as a whole, and the country contains languages from the three major African language families: Afroasiatic, Nilo-Saharan and Niger–Congo. Nigeria also has several as-yet unclassified languages, such as Centúúm, which may represent a relic of an even greater diversity prior to the spread of the current language families. Niger–Congo languages Niger–Congo predominates in the Central, East and Southern areas of Nigeria; the main branches represented in Nigeria are Mande, Atlantic, Gur, Kwa, Benue–Congo and Adamawa–Ubangi. Mande is represented by the Busa cluster and Kyenga in the northwest. Fulfulde is the single Atlantic language, of Senegambian origin but now spoken by cattle pastoralists across the Sahel and largely in the northeastern states of Nigeria, especially Adamawa. The Ijoid languages are spoken across the Niger Delta and include Ịjọ (Ijaw), Kalabari, and the intriguing remnant language Defaka. The Ibibio language is spoken across the coastal southeastern part of Nigeria and includes the dialects Oron, Annang, and Efik proper. The single Gur language spoken is Baatọnun, in the extreme Northwest. The Adamawa–Ubangian languages are spoken between central Nigeria and the Central African Republic. Their westernmost representatives in Nigeria are the Tula-Waja languages. The Kwa languages are represented by the Gun group in the extreme southwest, which is affiliated to the Gbe languages in Benin and Togo. The classification of the remaining languages is controversial; Joseph Greenberg classified those without noun-classes, such as Yoruba, Igbo, and Ibibio (Efik, Oron, and Annang), as 'Eastern Kwa' and those with classes as 'Benue–Congo'. This was reversed in an influential 1989 publication and reflected on the 1992 map of languages, where all these were considered Benue–Congo. Recent