* With an area of nearly 1 million square miles, Sudan is the largest country in Africa. Its population of more than 22 million is about 70 percent Moslem. Christians -- about 5 percent of the population -- and animists are concentrated in the south, where there has been unrest and separatist sentiment. Arabic is the official language. Literacy is estimated at 20 percent.

* HISTORY -- Egypt ruled much of Sudan from 1821 until 1885, when a nationalist leader calling himself the mahdi, or "leader of the faithful," defeated British Gen. Charles George (Chinese) Gordon at Khartoum and set up an independent state. In 1898, British and Egyptian forces under the command of H.H. Kitchener established a joint rule that lasted until independence in 1956. Jaafar Nimeri took power in a military coup in 1969 and established his Sudanese Socialist Union as the sole legal party. Initially an ally of Egyptian president Gamal Abdel Nasser, Nimeri became an ally of the United States after quelling a Communist-backed coup attempt in 1971. In 1972 he reached an agreement with rebellious southerners, ending a secessionist war that had cost a million lives. In 1983 Nimeri imposed strict sharia, or Islamic law, a particularly controversial move in the south.

* ARMED FORCES -- The Army of 53,000 includes two armored and seven infantry brigades. There is also a 3,000-man Air Defense Command equipped with SA2 missiles, an Air Force of 3,000 men with 34 combat aircraft and a 2,000-man Navy with about 10 patrol vessels.

* ECONOMY -- Sudan's mainly agricultural economy is dependent on the Nile River. The chief crops include cotton, gum arabic, sorghum, sesame, peanuts, rice and sugar. There are also small textile and food processing industries. Oil was found in the south, but development of the industry, including a planned pipeline, has been blocked by the rebellion in that region. With a per capita gross national product of $440, Sudan is one of the world's poorest countries. It depends heavily on aid from the United States, international agencies, and Saudi Arabia. The International Monetary Fund has pressed for changes in Sudan's economic policy, including devaluation of the pound and an end to food subsidies, that spurred the riots preceding the coup. Sudan's foreign debt stands at $9 billion and debt servicing for 1985 is estimated at $800 million, slightly higher than export revenues. Economic problems have been aggravated by the regional drought and by thousands of refugees from Ethiopia and Uganda.

* FOREIGN RELATIONS -- Sudan is Egypt's closest ally in Africa. The two countries are linked by a 1976 defense pact and a 1982 agreement on economic integration as a possible prelude to unity. Sudan and Libya have been at odds since 1972, when Nimeri rejected a bid for unity from Col. Muammar Qaddafi. Sudan is the largest recipient of U.S. aid in black Africa.