The last I saw of Nyamada Deng, she was walking off into the African bush holding her eight-year-old daughter by the hand and her three-month-old son clutched to her bosom. She wore a ragged, patched blouse over a floral skirt and, like both her children, she was barefoot.
The 21-year-old mother walked with a stately grace under the hot Sudanese sun, not once looking back as she set off in search of her village and the mother from whom she was taken a dozen years ago.
I paid $210 (£143) for the three of them to an Arab trader called Noor. Nyamada Deng and her two children were slaves and the money I paid secured their release. I have a picture of Nyamada and her children on my desk and, in one of the drawers, the receipt in Arabic given to me after I paid the money.
Were it not for this evidence I might have trouble believing what took place the day I met Nyamada and Noor, the Arab who hid his face behind the folds of his turban when I asked to take his photograph.
It was only a few weeks ago in the remote wilderness of southern Sudan that I witnessed a sight so strange, so medieval, that it might have taken place in another age. Yet the practice of slavery not only exists, it flourishes in the war-ravaged interior of Africa's largest country, in areas seldom visited by foreigners. Countless thousands of southerners have been abducted in raids by Arab marauders and forced into bondage in northern Sudan.
Nyamada and her children were among a group of 203 slaves recently returned to their Dinka tribal homeland by Noor, the Arab trader. They reached Bahr el Gazal (Gazelle River) province in southern Sudan, now threatened by famine, after walking for many days from villages in Southern Kordofan province where they had provided unpaid labour on Arab farms and in Arab homes.
They had been beaten and maltreated. Some of the women, among them Nyamada, had been subjected to genital mutilation and forced into concubinage. When I first came across Nyamada and her fellow-slaves they were sitting in the shade of a grove of mango trees near Wungiir, a straggle of thatched mud huts far removed from anything that might in the West be known as civilisation.
The location had been chosen by local Dinka elders as a suitable place for the transaction set to take place between Noor and Christian Solidarity International (CSI). CSI is a Swiss-based human rights organisation, which some critics term militant Christian or even Christian fundamentalist.
Since 1995 it has been paying Arab traders large sums of money to recover Dinka slaves from northern Sudan. The agency's work is facilitated by the rebel Sudan People's Liberation Army (SPLA) which controls most of the south. It is also approved by Dinka elders who want the return of their children and womenfolk. The slaves are paid for by CSI, then given their liberty. At first, such transactions took place secretly but, realising that that publicity would help fundraising, CSI unveiled its operations.
So it was that I came to accompany American John Eibner and German Gunnar Wiebalck on a clandestine mission to the front line of the conflict between government forces and southern rebels. And so it was that I came to pay $210 for a family I had just met to a man who was probably using a false name.
Earlier in the CSI mission to Sudan, Eibner had paid another trader 15 million Sudanese pounds (about £15,000, according to the rate of exchange he had secured) for 386 slaves. Enough money remained for the retrieval (or to use Eibner's preferred word "redemption") of a further 200 people; my contribution made up the shortfall.
CSI claims to have bought the freedom of some 1,400 enslaved Sudanese in recent years. But its programme prompts some disturbing questions. Does it, for example, encourage the taking of slaves by creating a lucrative market in an otherwise shattered economy? This and other questions must be answered. But, for the moment, let us return to the shade of the mango trees and the drama unfolding beneath them.
Eibner, bush hat pulled low over his bespectacled eyes, greets the turbaned Noor, and the two introduce their companions. Civilities completed, Eibner turns to the huddle of humanity arrayed before him.
"Greetings", he tells the upturned faces, "We're here to make sure you are free, free to go back to husbands, sons, mothers and fathers. No one should be afraid. We come in peace."
With a reassuring smile, Eibner returns to Noor who is seated on a leather-thong chair beside two other men wearing flowing Arab jalabiyas. The parties have done business before and, without ceremony, the discussion begins.
Through an interpreter, Noor points out that he sometimes has to bribe government officials to turn a blind eye to his scheme. Khartoum's Islamist-backed regime, locked in a bitter jihad or holy war against the African south, would not view kindly the return of infidel merchandise whose plunder is encouraged as an instrument of suppression.
"Yes, we know it's difficult and dangerous work you are doing," Eibner tells Noor. "We appreciate very much the risks you take. We too want these people returned to their families. We have brought the money with us and, if you're ready, maybe the exchange can begin." The bundles of notes are counted, then recounted under the watchful eyes of the Arabs. Finally, when both parties are satisfied, a handshake seals the deal and Noor waves dismissively in the direction of his human wares.
Realising they are at last free, they break into smiles and clap their hands. Local Dinka officials help me to interview some of the former captives. Among those I talk to is Nyamada. This is her story.
"I was captured in 1986, I know how long ago it was because I counted the harvests. My father was killed in the attack on our village. The man who took me away came on horseback. My hands were tied and I was made walk for seven days with the other children they had taken.
"I had to work in the kitchen of this Arab's house in the village of Makrenga [in Kordofan]. I fetched water and I also helped with herding his cattle. I was given the name Kaltuma and, when I was 14, I was told I was going to be circumcised. I didn't want it to happen but three women held me down and I was cut with a knife. It was very painful.
"The master already had a wife but he made me become his wife as well. At first I used to cry when he forced himself on me. If I refused to sleep with him he used to beat me with a thick stick. His other wife was jealous and used to fight with me. When my daughter was born, she was named Amina and when she was old enough they made her look after the goats and go long distances to get water. My son was named Hamid".
It was her Arab master's real wife who persuaded him to sell Nyamada to the trader. So it was that she finally returned to the land of her people.
"I hate these people, I'm very angry at what they did," Nyamada told me before walking off into the bush in search of her village. "Now I just want to find my mother. She's old now but I think I will recognise her."
Slavery has existed in Sudan for centuries. The northerners' word for a black southerner is abd, Arabic for slave.
Long before the white man started shipping captives from the shores of Africa, Arab traders were raiding along the Nile, deep into the equatorial communities of southern Sudan. African villagers were caught, roped together and taken northwards to be put to work or sold in slave markets, often for onward passage to Egypt and across the Red Sea.
Slavery was crucial to Sudan's economy in the last century, and most northern Sudanese were appalled when their Turco-Egyptian sovereigns tried to outlaw the practice in the 1870s. Even after slavery was outlawed by the British colonial rulers of Sudan which became a joint Anglo-Egyptian possession in 1899, the trade in humans continued.
Slaves were still being secretly sold in northern Sudan's markets during the early part of this century. By the time Sudan became independent in 1956, however, slavery had effectively died out. The practice reemerged only after the renewed outbreak of civil war in 1983, reignited when southern grievances turned to outrage over the government's attempt to impose sharia or Islamic law on the Christian and animist south.
As fighting between the northern forces and the SPLA rebels accelerated, the Khartoum government started arming Arab nomads in central Sudan and encouraging them to mount attacks on the southern tribespeople. What for generations had been low-level raids by the Baggara Arabs turned into systematic assaults in which whole Dinka communities were terrorised, villages razed and cattle, grain and people plundered as war booty.
The war gained new momentum with the seizure of power in 1989 by Lieut Gen Omar Hassan al-Bashir. His junta, controlled by the National Islamic Front (NIF) of fundamentalist ideologue Dr Hassan al-Turabi, vowed to crush the SPLA insurgency and subdue the infidel south.
The regular army was subsequently reinforced by the formation of a Popular Defence Force (PDF) into which large numbers of citizens were drafted. Arab nomads, mobilised into PDF units, are enticed with promises of rich rewards, specifically cattle and slaves.
Many of the raids are supported by regular army units and coincide with the movement of a government train which travels several times a year between the capital and the government-held town of Wau in Bahr el Gazal.
CSI's most recent mission to retrieve slaves took place in the aftermath of such a raid. According to community leaders in Bahr el Gazal, 1,500 PDF militiamen and about a thousand regular soldiers attacked eight settlements in Aweil West county on February 21st, 1998.
Making their way south with the train and accompanied by six tanks, the raiders, many of them on horseback, are said to have killed 37 civilians, captured 49 women and children, torched the houses of more than 500 families and looted more than 5,000 cattle.
Having watched Nyamada depart with her two children (by now given Dinka names), I walk back to the mango grove where the trader Noor still sits in his chair. At his feet lies a large white bag containing his earnings, 10 million Sudanese pounds (about £10,000 according to the rate CSI had secured in the south, but worth more than £34,400 at official Khartoum rates).
"I was a travelling salesman," he begins. "A few years ago some Baggara chiefs met Dinka chiefs and they reached an agreement. The Baggara said they would return captured children if they could graze their cattle on Dinka land in the dry season. The Dinka agreed to pay five cows for every child returned. I saw a business opportunity in this."
While it is tempting to see the trader as a war profiteer, the villagers have nothing but good to say of the man who rescues their children from servitude. The 39-year-old Noor confides that his own family, like most families in Kordofan, used to keep slaves. He himself was a member of the PDF and came several times to Bahr el Gazal on raids.
He says it seemed a normal part of war though it pained him to see humankind enslaved.
"The government is giving guns and money to encourage the [Baggara] people to attack," he says. "As long as that government in Khartoum exists, the raids will continue."
Noor explains he will soon return to his home up north where he will again start buying slaves for transport to the south. Before he leaves, he is promised by Eibner that CSI will before long return with more money. Noor seems satisfied and, clutching his bag of cash, he heads off into the bush.
The Sudanese government denies that slavery exists. Instead, it blames the practice of abduction on "tribal conflicts" in which hostages are taken captive. This is not a regime with an exemplary human rights record. Under Khartoum's Islamist junta, political dissent is crushed, torture is widespread, and children are taken for indoctrination and military training at special camps.
By neighbouring African countries as well as by the West, Sudan is accused of fomenting and exporting terrorism. All the more bizarre then that some people in public office should buy Khartoum's duplicitous line on slavery. Lord McNair, a British Liberal Democrat peer who last year visited Sudan as a guest of the Khartoum government said: ". . .we could find no evidence of slavery. . . the allegations of slavery made against the government of Sudan are unfounded."
Of course, it is not surprising that during his "field investigations" Lord McNair found no evidence of slavery; his visit to government areas was organised by the Khartoum authorities. He was hardly likely to come across slave markets because such markets do not exist, at least not in the sense that is generally understood. Southerners are not held in shackles for public auction.
According to the testimony of one of the Arab traders who does business with CSI, however, it is possible to buy slaves at cattle farms in Kordofan.
"You often find farms with more than 30 or 40 slaves, mostly boys who look after the cattle," says Ahmed, who admits his own father has slaves. "That's where you go if you want to buy someone to work for you. You can get a boy for about 45,000 [between £57 and £172 according to whether you calculate by the official or non-official rate]. Girls are more expensive because when they grow up they can be married."
That slavery exists in Sudan cannot be denied. A more interesting issue is the degree to which the Khartoum government should be held responsible. Again, there are some apologists in the West who seek to exonerate the NIF regime of involvement.
The survivors of Arab attacks testify to the participation of both government troops and government-sponsored militias in slave raiding. One Dinka man I met had recently had 12 children taken in a raid. Some of the attackers wore army uniforms and rode in vehicles mounted with machineguns. The government cannot be ignorant of their soldiers' and militiamen's involvement in slave raiding. Noor, himself a former PDF militiaman, says the raids are sanctioned by the highest authorities.
"Turabi [widely regarded as `the power behind the throne] visited Kordofan earlier this year and held mass rallies," says Noor. "He told the [PDF] recruits the time had come to attack the infidels and wage jihad against the Dinka."
Among organisations which have in the last year condemned the Khartoum regime for permitting slavery to continue are the United Nations Commission on Human Rights, the US Department of State and the British Foreign Office.
The Irish Government has been less outspoken on the question of slavery in Sudan, preferring to criticise both sides in the conflict for human rights abuses rather than single out the Khartoum government for censure.
In a recent statement, Liz O'Donnell, Minister of State at the Department of Foreign Affairs, said: "We condemn all those responsible for human rights violations and particularly those who so ruthlessly and selfishly violate the rights of innocent children including through child slavery."
We are flying in a light aircraft at 10,000 feet over the tawny scrub of southern Sudan. The outline of a village or the winding line of a path is occasionally visible, but otherwise there is no sign of life. This is one of the most underdeveloped places on earth: there are no tarmac roads, hospitals, supermarkets, electricity or running water.
We have just left a land whose inhabitants are living close to the Iron Age. They carry spears. They live in mud huts and cook on open fires. They have threadbare clothes, some pots and pans, and of course their cattle, but little more.
The SPLA rebels are armed with modern weapons, but they too often go barefoot and ragged. We have left a primitive place and, cruising smoothly through the skies, we are dreaming of cold drinks and a decent meal.
"The mission went pretty well," says John Eibner in reply to my query. "We achieved our goal, we redeemed the slaves."
I think about the poverty of Sudan and the impact of CSI's dollars on such a brittle economy. How does CSI know it is not unwittingly encouraging slave-raiding? CSI says all the evidence points to a decline in slaveraiding, not because of its retrieval programme but because the Baggara Arabs, increasingly resistant to government manipulation, are staging fewer raids.
Before CSI arrived on the scene, there already existed a structure whereby the Dinka paid with cattle for the return of their enslaved women and children. Is CSI not worried it is inflating the price for slaves, making Dinka communities pathetically dependent on Western largess?
"We pay 50,000 Sudanese pounds per slave, the equivalent of five cows," says Eibner. "The rate was agreed between Dinka and Arab elders before we arrived. The Dinka themselves welcome us and are urging us to continue."
I remember my conversation with Ahmed, the trader who after selling 386 slaves to CSI could hardly get out of his chair, so great was the pile of cash on his lap. Ahmed, enjoying a celebratory cigarette, had confided to me that formerly he had got just a few cows for the slaves he delivered. CSI was paying him three times as much as he used to get, he said with prid. His profit for the return of 386 slaves was at least four million Sudanese pounds (£14,400 according to the official exchange rate).
In a land whose economy is ruined, where barter is common and where exchange rates vary with the weather, it is difficult to establish the true value of money. And, if women and children are reunited with their families, maybe none of these quibbles matters too much. Still, some nagging doubts must remain.
A number of people have asked me what will become of Nyamada Deng and her two mixed-race children. Will they reintegrate into Dinka society? Will she be accepted after what has happened to her? Will she find a husband?
Dinka culture is a caring one and family ties are sacred. There is every reason to believe Nyamada and her children will prosper. When last I saw their faces they were smiling.