Scorching heat, congested camps and a perilous journey await many fleeing Sudan's violence

The exhausted donkeys pulling carts overloaded with people and luggage across the border into South Sudan look as though they could buckle and collapse at any moment.

The same could be said of the fragile nation the new arrivals are fleeing to.

South Sudan, statistically the poorest country in the world, is being overwhelmed by an exodus of people fleeing the bloodshed in neighbouring Sudan.

A team from CBC News visited the remote border region between the two neighbours recently, an area which is extremely difficult for Western news organizations to access.

Before 2011, Sudan and South Sudan were part of the same country and still share some common demographics and culture. South Sudan has suffered from its own extreme violence in recent years, but after the first clashes in Sudan's capital of Khartoum on April 15, people in the north began streaming across its open border. 

Since then, aid agencies estimate more than 400,000 people have left, with roughly 80,000 arriving in South Sudan.

United Nations officials said last week they fear that number could double or even triple in the months ahead if Sudan's army and the paramilitary group it's fighting don't make peace.

The violence in Khartoum has been especially vicious, with reports on Wednesday of 19 people killed and more than 100 injured in an attack on a city market.

The Wunthou border crossing, near the South Sudanese town of Renk, is the most direct route south for people trying to get out of Khartoum, an eight-hour drive away.

In oppressive 40-degree heat, families sat on rugs and suitcases, using donkey caravans to cross the final few hundred metres of no man's land.

"It's bad," said Hafiz Mohammed Ali, who spoke to CBC News just as he, his wife and four young children crossed the frontier. "Aircraft are [bombing] lots of places, so I just wanted to bring my family and be safe."

Another man, Issac Pham Vissel, also described aircraft bombing military buildings near his house, and said he and his family needed to get out.

"It's a very serious war," he said. "And I think it will be continuous."

A succession of ceasefires have come and gone with little effect.