By Ishbel Matheson
BBC correspondent in southern Darfur
There are signs of a scorched earth policy
In the rocky desert of western Sudan, heat-waves shimmer on the horizon.
There are scrubby trees, the occasional flock of sheep, grazing peacefully, but otherwise, the countryside is empty.
No farmers tending crops, no women fetching water, no children playing in the dust.
As we drive out from the main town of Nyala, in southern Darfur, we begin to see the evidence of lives swiftly overturned.
In the first village, ash crunches underfoot.
Huts are charred, the thatch gone.
In the debris is a child's blue plastic shoe.
In the second village, clay water pots lie cracked open like eggs.
A grain store is scorched and empty.
In the huts, there is a muddle of cloth, wooden beds half broken, buried under a thin layer of dust.
For months, the Islamic government in Khartoum, together with traditional Arab militia, have been accused of pursuing a scorched earth policy in western Sudan.
Everything we saw, everything we heard, suggests that this is true.
Strung out along our route, are more deserted, torched villages.
In all of them, the signs are of a hasty, panicked departure.
Up to one million people - a sixth of the population of western Sudan - is believed to be on the move.
The Sudanese of African descent have been "cleansed" from their traditional lands, forced to become refugees in their own homeland.
The government claims it has been trying to put down a rebellion in Darfur.
It says the rebels, from the Darfuri African community, hide among the villages.
These communities, it implies, are simply caught in the crossfire.
But the refugees have a different story.
We find thousands of them camped on stony ground, at Kalma, a few miles from Nyala.
We have been told that people might be too scared to speak in front of our government minders.
But as the crowd presses around us, there is a feeling of anger and desperation.
We are the first journalists they have seen, and they are eager to testify to what happened to them.
A 13-year-old girl, Hawa, steps forward.
She escaped to Kalma after her village was torched.
She identifies the attackers as Arabs on horseback, accompanied by government planes.
She and her six sisters managed to run away, but her parents were killed.
She takes us to the fragile straw and stick hut where the little girls have set up house.
Everywhere there are signs of hasty departures
Hawa cradles her three-year-old sister.
A battered pot, containing a little porridge, sits outside.
During the attack, the family's livestock - cows and horses - were also lost.
The family is now destitute.
Kultam Omar, 21, has a similar story.
She says she lost her husband, brothers and aunts in an attack on her village.
"The government and the Arabs come together. They kill and they shoot from the planes."
The government in south Darfur flatly denies these charges.
When we put the refugees' testimony to the Minister for Social Affairs and Culture, Jadain Jul-Alleh Daagage, he attributes it to rebel propaganda.
"It is the politicians who have put the idea in the mind of people."
For generations, the two Darfuri communities - African farmers and Arab nomads - have been rivals for the scant resources, the water and pasture, of western Sudan's harsh landscape.
But the conflict resolution think-tank, the International Crisis Group, says a decisive factor in this war has been the help given to the pro-government militia.
A recent report concluded: "These 'Janjaweed' militias have over the past year received greatly increased government support to clear civilians from areas considered disloyal."
The Khartoum government flatly denies this charge.
The 'Janjaweed' militia are accused of ethnic cleansing
A senior government official in south Darfur is Ahmed Ngabo Ahmed.
Asked whether the government has armed the militia, he emphatically says: "Never, never."
The humanitarian consequences of this war have been catastrophic.
The United Nations has described the situation in Darfur as a crisis of "enormous proportions".
The survival of the hundreds of thousands of displaced is on a knife-edge.
Under intense pressure from the international community, the Sudanese government has reluctantly agreed to allow the delivery of international aid.
But humanitarian workers are gloomy about the future.
They talk privately of bureaucracy obstructing the delivery of help.
The rains are also due to arrive shortly, and with them, the increased threat of disease and hunger.
Lack of medicine
In a disused secondary school in the village of Kass, an emaciated three-year-old girl takes rasping breaths.
A local health worker shakes his head.
The child is not expected to live.
He estimates three children a day are dying.
"Do you have any medicine?" he asks us.
There is no medicine, and little food.
As we arrive, the first distribution of grain is about to begin.
The people seem dazed, sitting listlessly on reed mats.
They have just escaped a terrifying ordeal.
For weeks they were held hostage in a village, surrounded by the militia.
Food was running perilously short, and they came under constant attack.
Witnesses say government officials in cars accompanied the militia.
The imminent arrival of a UN humanitarian mission in the village finally secured their release.
The UN sees the long-term solution to the Darfur crisis as the re-settling of the displaced back in their villages.
But there is little evidence that the government is willing, or able, to rein in the militia.
When we ask the refugees whether they think of returning home, their reply is emphatic.
No-one will consider going home as long as the militias are on the rampage.
Out in the countryside, the land has already been turned over to other use.
Amid the scattered ruins of other people's lives, nomads now graze sheep and cattle.