JAMAM, South Sudan -- Needing water, the teetering mass of people lurched forward, some dropping to the ground in thirst, unable to walk any farther. The tens of thousands of refugees already had marched hundreds of miles over weeks of grueling terrain to cross into South Sudan, but they still hadn’t reached a United Nations refugee camp.

The aid group Doctors Without Borders set up emergency clinics along the way, saving some lives but losing others.

“There was no food and there was no water,” Abukar Joda, wearing a torn secondhand shirt, said of the long journey. “Many died because we couldn’t find water.”

The thirsty refugees pouring out of Sudan’s Blue Nile state are only a fragment of the vast human toll in Sudan, where hundreds of thousands of people are starving to death and fleeing their homes in war-torn lands whose names are unknown to most outsiders. The border district of Abyei has been razed and its population driven out, the famished Nuba Mountains are coughing out a steady stream of starving refugees and Blue Nile is a desolated war zone of abandoned villages.

These hot spots – known in diplomatic circles as the Three Areas – have pushed 270,000 refugees into South Sudan, tens of thousands into Ethiopia and untold others into neighboring Sudanese states to seek safety.

As South Sudan this week marks one year since it gained independence from Sudan, the squabbles and occasional military flare-ups between the uneasy neighbors continue to overshadow the fates of these border populations in Sudan despite the hundreds of thousands of lives that are hanging in the balance – and the fact that one-third of a U.S.-backed peace deal originally was directed toward resolving the conflicts in the Three Areas.

Before South Sudan’s January 2011 referendum on independence, fears of renewed north-south war led international diplomats and Sudanese officials to push the rest of the 2005 peace deal to the back of the agenda, said Jon Temin, the Sudan director at the U.S. Institute of Peace, a research center. The result, Temin said, was that South Sudan was able to secede largely without violence, but the rest of the peace deal’s provisions were left in shambles.

“This was a tradeoff that politicians and diplomats chose to make,” Temin said.

That strategy seems to have backfired.

U.S. officials now consider the raging war in the Nuba Mountains and Blue Nile a chief obstacle to resolving the violent border disputes between Sudan and South Sudan. In a recent interview, Princeton Lyman, the ranking U.S. envoy to Sudan and South Sudan, said he was “very pessimistic” about the prospects for cross-border peace unless the conflicts in those areas resolved first.

Any satisfaction that U.S. and other diplomats felt at overseeing Sudan’s partition after decades of north-south conflict was short-lived, with the fighting erupting before South Sudan’s secession was even official.

In May 2011, Sudanese forces swept through Abyei – a disputed district along the border that’s inhabited by ethnic South Sudanese but used as a grazing ground by nomadic northerners – and drove South Sudanese off the land, displacing some 100,000 people.

A month later, fighting erupted in the Nuba Mountains, and then spread to Blue Nile last September as Sudanese forces tried to dislodge the Sudan People’s Liberation Army-North militia, which had fought previously alongside South Sudan but refused to disarm until the peace deal provisions were fully implemented.