South Sudan gained independence from Sudan in July 2011 as the outcome of a 2005 peace deal that ended Africa's longest-running civil war.
An overwhelming majority of South Sudanese voted in a January 2011 referendum to secede and become Africa's first new country since Eritrea split from Ethiopia in 1993.
The young state plunged into crisis in December 2013 amid a power struggle between the president and his deputy whom he had sacked.
Fighting between government troops and rebel factions erupted into a conflict that had killed thousands and prompted more than 2.2 million people to flee their homes by the time a tentative internationally-mediated peace agreement was signed in August 2015.
The new nation stands to benefit from inheriting the bulk of Sudan's oil wealth, but continuing disputes with Khartoum, rivalries within the governing party, and a lack of economic development cloud its immediate future.
Formed from the 10 southernmost states of Sudan, South Sudan is a land of expansive grassland, swamps and tropical rain forest straddling both banks of the White Nile.
It is highly diverse ethnically and linguistically. Among the largest ethnic groups are the Dinka, Nuer and Shilluk.
Unlike the predominantly Muslim population of Sudan, the South Sudanese follow traditional religions, while a minority are Christians.
As Sudan prepared to gain independence from joint British and Egyptian rule in 1956, southern leaders accused the new authorities in Khartoum of backing out of promises to create a federal system, and of trying to impose an Islamic and Arabic identity.
In 1955, southern army officers mutinied, sparking off a civil war between the south, led by the Anya Nya guerrilla movement, and the Sudanese government.
The conflict only ended when the Addis Ababa peace agreement of 1972 accorded the south a measure of autonomy.
But, in 1983, the south, led by the Sudan People's Liberation Movement (SPLM) and its armed wing, the Sudan People's Liberation Army (SPLA), again rose in rebellion when the Sudanese government cancelled the autonomy arrangements.
At least 1.5 million people are thought to have lost their lives and more than four million were displaced in the ensuing 22 years of guerrilla warfare. Large numbers of South Sudanese fled the fighting, either to the north or to neighbouring countries, where many remain.
The conflict finally ended with the 2005 Comprehensive Peace Agreement, under which the south was granted regional autonomy along with guaranteed representation in a national power-sharing government.
The agreement also provided for a referendum in the south on independence in 2011, in which 99% of southern Sudanese voted to split from Sudan.
Long based on subsistence agriculture, South Sudan's economy is now highly oil-dependent. While an estimated 75% of all the former Sudan's oil reserves are in South Sudan, the refineries and the pipeline to the Red Sea are in Sudan.
Under the 2005 accord, South Sudan received 50% of the former united Sudan's oil proceeds, which provide the vast bulk of the country's budget. But that arrangement was set to expire with independence.
In January 2012, the breakdown of talks on the sharing of oil revenues led South Sudan to halt oil production and halve public spending on all but salaries.
A deal in March 2013 provided for Sudan to resume pumping South Sudanese oil in May, and created a demilitarised border zone.
Despite the potential oil wealth, South Sudan is one of Africa's least developed countries. However, the years since the 2005 peace accord ushered in an economic revival and investment in utilities and other infrastructure.
Alongside the oil issue, several border disputes with Sudan continue to strain ties. The main row is over border region of Abyei, where a referendum for the residents to decide whether to join south or north has been delayed over voter eligibility.
The conflict is rooted in a dispute over land between farmers of the pro-South Sudan Dinka Ngok people and cattle-herding Misseriya Arab tribesmen.
Another border conflict zone is the Nuba Mountains region of Sudan's South Kordofan state, where violence continues between the largely Christian and pro-SPLA Nuba people and northern government forces.
Inside South Sudan, a cattle-raiding feud between rival ethnic groups in Jonglei state has left hundreds of people dead and some 100,000 displaced since independence.