FACTBOX-Violence stalks troubled Sudan

(Reuters) - Darfur rebels fought with Sudanese government troops in a Western suburb of the capital on Saturday and said their aim was to overthrow President Omar Hassan al-Bashir. The government said the attack had been defeated.

Here are some key facts on Sudan and its conflicts:

* Sudan is Africa's largest country with an area of 2.5 million sq km. It straddles the middle reaches of the Nile and is bordered by Egypt to the north; the Red Sea, Ethiopia and Eritrea to the east; Kenya, Uganda and the Democratic Republic of Congo to the south; and the Central African Republic, Chad and Libya to the west.

* Oil exploration began in the 1970s, but operations were repeatedly interrupted by war, with southern rebels laying claim to oil fields that provided the government with vital revenue.

* In 1983, the Sudan People's Liberation Army (SPLA), the main southern rebel group led by John Garang, launched a war against the northern-based government, partly sparked by the imposition of Islamic law, sharia, by the then-government.

* The war pitted the black African south, which is mainly Christian and animist, against the mainly Muslim, Arabic-speaking north. The war was complicated by tribal and factional fighting, as well as the conflict over oil.

* In 2004, a deal, sealed by the SPLA and the Khartoum government, cleared the way for a comprehensive peace to end the 21-year-old civil war in the south that claimed more than 2 million lives.

Darfur in the west:

* Rebels rose up against the government in February 2003 saying Khartoum discriminated against non-Arab farmers in Darfur in favour of Arab tribes. More than 2 million Muslim Darfuris, mainly subsistence farmers from a wide variety of ethnic groups for whom Arabic is a second language, have fled their homes.