Nigeria's 110 million population is dominated by three ethnic group. The largest group are the Hausa. They are predominantly Moslem, speak a language heavily influenced by Arabic and most live in the north. For centuries the well organized and energetic Hausa have dominated much of Western and Central Africa. They dominate the government of Nigeria. The next largest group are the 30 million Yoruba, who live in the Southwest. The Yoruba are enthusiastically Christian and much in favor of technical and economic progress. Yorubas dominate the professional classes in Nigeria. The third largest group is the Ibo, who dominate in the southeast. Also largely Christian, the Ibo have long been noted as traders and entrepreneurs. Instead of the more traditional tribal system, the Ibos have long organized themselves in clans. The remaining 20 million Nigerians belong. to some 200 different ethnic groups, many of which are being slowly absorbed by the larger ones. In the south, Christian Ibos have been killing any Moslem Hausas they could find, and causing thousands of Hausas to flee for their lives. This violence was triggered by reports that Christian Ibos and Yorubas in the north were being killed by Moslems. The governors of three northern states have agreed to revoke Sharia law for the moment, because of the violence. The president has called an emergency meeting of provincial governors and other officials to discuss the spreading religious violence.