(CNN) -- Several million people began deciding Sunday whether to give birth to the world's newest nation.
They started casting ballots on whether to declare independence at polling stations sprinkled across the vast, flat plains of Southern Sudan, an East African landscape long riven by chaos.
War and famine have ravaged generations in the south for as long as anyone can remember. Fighting forced more people from their homes than in any other nation on earth. Hope remained elusive.
Yet the vote has given many southerners the rare sense of exhilaration that is borne of new beginnings.
For the next seven days, the black Christians and animists in the autonomous region of Southern Sudan will vote on whether to declare independence from a northern government dominated by Arab Muslims. The two sides fought a war that killed 2 million people from 1983 to 2005, when a peace treaty set the stage for the upcoming vote.
Nearly 4 million have registered to cast ballots. Few doubt the outcome.
"I have not encountered a single Southern Sudanese who is interested in voting for unity. I would say at least 98 percent of them will vote for separation," says Ezekiel Lol Gatkuoth, a former foot soldier in the southern rebel force who now leads the Southern Sudan's mission in the United States. "This is what we have been fighting for for more than 50 years."
Voters awoke early Sunday in the bustling capital of Southern Sudan, Juba. Mary Dennis arrived at a polling place at 4:30 a.m.
"I had to come early," Dennis says. "This is a vote for our country."
Edwina Loria, 18, also was determined to cast her ballot.
"I want to be a first-class citizen," she says. "I want independence."
"I am on a mission," says another voter, John Baptiste. "My mission is to vote. We have waited for 50 years, and we want to be separate. We have planned for many days to be here first."
Voters are receiving a ballot with two pictures: One hand signifies independence; two hands, a unified Sudan.
Most everyone agrees that the majority of southerners will choose independence, but there is less certainty about what will happen after the votes are tallied.
The new nation would face daunting obstacles, from a desperate need for development to the lack of a robust educated class to control the new levers of power.
A flood of refugees, eagerly returning to an independent homeland, could complicate matters in a place that already lacks enough schools and clinics and has few paved roads.
Long-standing grievances among rival southern groups could erupt in violence -- several hundred southerners already have been killed in such fighting in the last year or two. Or the north could decline to accept the results or stir tensions by trying to pit one southern faction against another.
The concerns run so deep that last February Dennis Blair, then the director of national intelligence, warned the U.S. Congress of possible genocide.
"A number of countries in Africa and Asia are at significant risk for a new outbreak of mass killing" in the next five years, he said. "Among these countries, a new mass killing or genocide is most likely to occur in Southern Sudan."
Looming over concerns about the future is a suspicion that many in the south harbor of Sudan's rulers in the north.
Sudanese President Omar al-Bashir, wanted for war crimes after mass killings and rape in the country's western Darfur region, says that a southern vote for independence would be like "cutting off a part of the nation's body but not the end of the world."
"We are a civilized people," he said this week in a rare visit to Juba. "Regardless of how painful the results are, we will greet the result with forgiveness, and patience, and acceptance, and an open heart, God willing."
Al-Bashir also has said that his government will not hesitate to accept the results "because peace is our ultimate goal in our relationship with our southern brothers, even if they choose a path other than unity."
Yet many worry that the northern-based government will interfere with the referendum, decline to recognize its outcome or stoke tensions between rival southern factions.
The possibilities concern Abdullahi An-Na'im, a native of northern Sudan who teaches law at Emory University in Atlanta, Georgia. He is a former executive director of Human Rights Watch for Africa and an expert on Islamic law, or sharia. Authorities in Sudan imprisoned him in the 1980s for opposing the imposition of Islamic law in all of Sudan.
He looks to the past for clues to the future.
"The history of Sudan is such that I cannot expect the northern government to have the grace and humanity to let the south go peacefully," he says.
A troubled history
People in Southern Sudan -- and their ancestors -- have long felt dominated by the north.
One of the first known instances of contact between the two regions, historians say, came when slave-raiding parties from the north penetrated a vast swamp between northern and southern Sudan around 1840.
The slave raids so terrified the largest southern tribe, the Dinka, that some refer to this period as the "spoiling of the world," a time when outsiders violently transformed everyday life, writes Francis Deng, a Sudanese diplomat, author and historian who is the United Nations' special adviser on the prevention of genocide.
The slave raids instilled a collective hostility toward northerners that successive generations in the south nursed until they erupted in open war.
Britain ruled Sudan from 1899 through 1955 and administered north and south as separate entities, preventing travel from one region to the other. As a result, people in the north, home to about two-thirds of Sudan's land and population, saw more development and formal education, while the south remained, Deng writes, "largely a museum of nature."
That imbalance sparked southern fears of northern domination when the British announced plans to leave.
Southerners took up arms against the north in August 1955, six months before Sudan's independence. Most jobs in the new national government did, in fact, go to northerners. The north also dominated the process of drafting a constitution.
An-Na'im sees in many northerners a "deep-rooted racism and imperial attitude" and a "sense of superiority" toward southerners.
Many northerners have a mix of Arab and black ancestry but "deny the strongly African elements in their skin color and physical features. They associate these features with the negroid race and see it as the mother race of slaves, inferior and demeaned..." he writes in his 1995 book "War of Visions: Conflict of Identities in the Sudan."
The insurgency that started in 1955 killed several hundred thousand people and forced many more from their homes until a peace deal silenced the guns in 1972. Barely a decade later, though, war resumed after the Sudanese president split the south into three regions and sought to impose Islamic law on non-Muslims.
A 1989 coup that brought al-Bashir to power let him steer the ship of state by the compass of Islamic extremism. He praised the 1979 Iranian revolution and offered shelter to many groups the United States views as terrorist organizations.
Osama bin Laden arrived in Sudan in 1991, long before he became a household name. The United States added Sudan to its list of state sponsors of terrorism two years later.
Meanwhile, the north-south war raged on.
Human-rights groups would document a catalog of horrors, from the widespread killing of civilians to the forced recruitment of child soldiers, but the carnage and misery attracted relatively little attention in the West. '
Separation is the only way out'
About 10 years ago, neighbors in East Africa and the West pushed both sides toward the negotiating table.
Some of the pressure came from the United States, where President George W. Bush made ending the war in Sudan a top foreign policy priority in Africa. Bush was responding to political pressure from conservative evangelical Christians, who have empathized with Christians in Southern Sudan.
Peace talks were well under way in 2003 when a mostly unrelated conflict erupted in the western Sudanese region of Darfur. Marginalized non-Arab Muslims there rebelled against the government by attacking a military garrison.
The Sudanese government responded by arming and cooperating with Arab militias that killed, tortured and raped thousands, mainly targeting tribes from which the rebels drew strength, according to the United Nations, Western governments and human rights organizations.
The United Nations says 300,000 people have been killed and 2.5 million displaced in Darfur, though the government of Sudan says the toll is lower.
Al-Bashir's role in Darfur led the International Criminal Court to indict him for war crimes in 2009.
Even as the killing continued unabated in Darfur, al-Bashir's government made progress in negotiations with southern rebels. That progress resulted in a landmark agreement in January 2005 between the Sudanese government and the main rebel group in the south, the Sudan People's Liberation Movement. The Comprehensive Peace Agreement called for the referendum that is to begin in a few days.
It also envisioned a vote in Abyei, an oil-rich area that the British transferred to northern Sudan in 1905. The agreement says people in Abyei should vote on whether to remain part of the north or return to the south.
Both sides were to have worked out many details by now, but that has not happened, delaying the referendum in Abyei.
One unresolved issue involves who should vote: Should it only be members of the Ngok Dinka ethnic group, who tend to have more in common with southerners, or also the Misseriya, a nomadic Arabic tribe that comes in and out of the region and whose sympathies would most likely tilt toward northern Sudan?
Despite the delay in Abyei, vote on independence has proceeded as planned in Southern Sudan.
While most of the voters will cast ballots in Southern Sudan, about 120,000 southerners in northern Sudan have registered to vote, Gatkuoth said. Another 55,000 -- mostly refugees -- have signed up to vote in Australia, Canada, Egypt, Ethiopia, Great Britain, Kenya, Uganda and the United States.
A few thousand people from Southern Sudan will cast ballots in Boston, Chicago, Dallas, Nashville, Omaha, Phoenix, Seattle and Washington.
One is Simon Garang, a 28-year-old college graduate who earns money parking cars at the Ritz-Carlton hotel in Atlanta. He planned to join other natives of Southern Sudan traveling in a caravan from Atlanta to Nashville on Sunday to vote.
"It is really important for me to vote because Southern Sudanese will have the chance to live as a free country," he says. "The reason I am going to vote is to express my will for the freedom of Southern Sudan."
Garang was separated from his parents during the war in the south in the 1980s and came to the United States as a refugee in 2001, after a childhood and adolescence spent dodging death and disease on treks from one refugee camp to another.
"History proves that the north and south are not supposed to be together," he says. "I think separation is the only way out of the current crisis."
The world is watching
A successful referendum would represent a triumph for Southern Sudan, but also for world leaders who have exerted pressure on both sides.
They include President Barack Obama, who discussed Sudan at the United Nations in September.
"At this moment, the fate of millions of people hangs in the balance," Obama said then. "What happens in Sudan in the days ahead may decide whether a people who have endured too much war move towards peace or slip backwards into bloodshed."
The U.S. has raised the possibility of removing Sudan from its list of state sponsors of terrorism if the government recognizes the referendum results, senior State Department officials have said.
It also has sounded the alarm about possible calamity in the south -- Secretary of State Hillary Clinton called the situation in Southern Sudan "a ticking time bomb of enormous consequence" in September.
Sen. John Kerry, chairman of the Senate Foreign Relations Committee, arrived in Southern Sudan last week on his fourth trip to Sudan.
"The United States played an important role in ending the civil war in Sudan and making the vote this Sunday possible," he said. "Our commitment to the Sudanese people will extend beyond the referendum, whatever its outcome, as we work to improve economic and humanitarian conditions in the region."
An-Na'im sees the referendum as a turning point.
"It is historic, but in a negative sense to me," he says. "I regret that the Sudanese of the north have failed to make unity attractive enough for Sudanese from the southern part of the country."
He's sad about the possibility of his country dividing, he says, but he doesn't blame southerners. If he could vote, he says, he'd choose independence, too.
After the voting
Both sides will have a lot to figure out if the south elects independence.
For one thing, the northern-based government would lose tremendous oil revenues. A
s much as 70 to 80 percent of Sudan's known oil reserves are in the south, says John Prendergast, an Africa expert and frequent critic of the Sudanese government. He also co-founded the Enough Project, which seeks to end genocide and crimes against humanity. "It's literally billions and billions of dollars over the next decade," he says. "It's the lifeblood of the economic growth and prospects for economic development in northern Sudan as well as in Southern Sudan."
Losing a share of that oil revenue could cause economic hardship in the north. The government also could face criticism for "losing" the south, possibly making al-Bashir's political position more tenuous, says Jennifer G. Cooke, director of the Africa program at the Center for Strategic and International Studies in Washington.
"There is still such a deep layer of mistrust between the north and south," she says.
Sudanese Foreign Minister Ali Karti says his government will respect the results no matter the outcome -- as long as it and other bodies, such as the African Union and the United Nations, are "convinced that it (the referendum) has been done the right way.
"We have been engaged in a civil war for 60 years. We sat down (and) signed an agreement ... well aware that such self-determination may or may not end in secession."
Yet the foreign minister also accused the south of hosting rebels from Darfur.
"This is a declaration of war, and we will not at all accept it," he said. "For them to have a new state, to celebrate that ... is good, but to host leaders of the rebels of Darfur and even give them some ammunition, cars and everything, that is not acceptable at all."
In response, Gatkuoth said the government of Southern Sudan "is not in any way supporting militarily the rebels from Darfur."
The government and the former rebel force, the Sudan People's Liberation Movement, he said, "are committed to peace and we are working with all parties involved to bring peace to Darfur."
Formal results from the referendum are to be announced February 2, Gatkuoth says.
If the south chooses independence, north and south would enter a six-month negotiating period before the south emerged as an independent nation on July 10.
Before then, negotiators would wrestle with an array of thorny questions. Are the several million southerners who have lived in northern Sudan for years, for example, citizens of Sudan or the new nation?
They also would have to decide what share of the national debt the south should inherit, Cooke says.
Perhaps most tricky of all is the question of how to share oil revenues, which account for about 90 percent of the south's budget. The two sides depend on each other when it comes to oil -- most oil in Sudan comes from wells in the south but must flow through pipelines in the north for export.
"Many of these issues should have been resolved by now, but they have not," Cooke says. "Both sides have been playing a bit of brinksmanship."
Would the new nation be called Southern Sudan, as the autonomous region is known? Or perhaps New Sudan, as the main southern rebel leader, John Garang, sometimes called the region? Maybe something else altogether?
Gatkuoth laughs off the question.
"When your wife is pregnant, sometimes you wait for the baby to be born," he says. "We are still debating what to call this new baby." He knows obstacles will linger long after the exuberance of creation fades.
Southern Sudan lacks basic infrastructure and strong institutions of government. There is no banking system, Cooke says, no currency. The challenge is to maintain security while also trying to breathe life into a nascent economy where military service has long represented one of the few solid career choices.
"You're really talking about transforming what has been for many years a rebel movement into a government," Cooke says.
Exacerbating the challenges is the flood of southerners returning home. About 95,000 returned in the last two months, about five times the number that arrived in all of 2009, according to the United Nations Mission in Sudan.
Sarah Bony and Thatiosis Misantuta are two of the many returning southerners.
They were born in Khartoum in 1992, during some of the most intense fighting in the south, and spent their whole lives there, amid hundreds of thousands of other displaced southerners.
A week or so ago, however, they said goodbye to the only home they'd ever known and flew to what they consider their native land.
"We were second-class citizens in the north," Misantuta says through a translator under a searing sun in Juba. "We are willing to undergo anything as long as we are separated."
He is optimistic about the future.
"I think there will be peace," he says.
Bony is not so sure.
She worries that disagreements over borders or sharing oil wealth or disputes between rival groups in the south could plunge the south back into an abyss of misery.
It happened in 1991, when rival factions of the southern rebel force turned on each other in the midst of the north-south war, killing scores and weakening the collective southern position against the north.
As the referendum approached, north and south spent money buying weapons.
"While a renewed conflict could be limited to proxy fighting or skirmishes focused around individual oilfields, both sides' arms purchases indicate their anticipation of more widespread conflict," Blair, the former U.S. intelligence director, said in a report to Congress last year.
"The southern government is spending a large amount of its revenues on military force modernization while failing to provide basic services, curb rampant corruption or curtail escalating tribal clashes," he continued. "Some international observers have suggested the south will become a failed state unless the international community assumes a significant role in development, security and governance."
Gatkuoth has heard the warnings, but says the south will fare better than some analysts predict.
After decades of near-constant carnage, he says, southerners are standing, at last, on the cusp of something new. H
e says he believes his countrymen will surmount the vexing challenges that await without returning to the cycle of war and displacement that have scarred generations.
Southerners don't want to go back to war, he says. They just want to live in peace.
CNN's David McKenzie and Ingrid Formanek and journalists Nima Elbagir and Shannon Jensen contributed to this report from various locations in Sudan.