UPDATE In a referendum of January 2011, the south of Sudan voted to separate from the north; and in July 2011 South Sudan became the world's newest country.
A separate war in the western Darfur region has killed more than 200,000 people and driven two million from their homes.
Despite the importance of oil in a Sudanese economy that has expanded as a result, agriculture is still the main industry. A combination of war and drought means that many live at subsistence level - with little income, relying on the land for day-to-day provision.
Christians in Sudan
The Christian church in Sudan has not only endured, but grown through decades of war, poverty, famine and the attempted imposition - often by force - of Islamic shari'a law by the government in Khartoum.
Christians in the south of Sudan regularly endured attacks and bombings of schools, hospitals and churches. Pastors and leaders were persecuted, attacked and even killed. Yet Christian communities responded with a spiritual and practical resilience and much church growth resulted, despite the intention of Khartoum to eradicate Christianity altogether.
Further north, in Arabic-Muslim Khartoum and surrounding regions, and in the western province of Darfur for example, Christians are far fewer and those who are believers face many difficulties.
Yet there are historic populations of Coptic Christians, and significant numbers of believers displaced from the south. There are even reports of pockets of church growth, especially in communities where evangelistic effort has encountered hearts disillusioned with Islam and open to the gospel.