When the war in the Nuba Mountains in Sudan's South Kordofan state began in 2011, thousands of Nuba people fled to neighboring South Sudan. They settled close to the border in Yida where they built a market, workshops, houses and schools.

Every morning at the Yousif Kuwa primary school in the Yida camp, the day begins with two thousand students singing an unofficial national anthem celebrating the Nuba Mountains.

Although 70,000 Nuba refugees live in Yida, the UN refugee agency, UNHCR, does not recognize it as an official refugee camp. This means there is no UN assistance for the school.

Fatoumata Lejeune-Kaba, who works for the UNHCR, told DW Yida is a militarized zone and refugees would normally never have been settled there by any aid organization. The refugees settled there themselves but now they are leaving.

"The government asked us to close down our operations in Yida by June 30. The government is responsible for the safety of the refugees; they want to make sure that refugees are assisted where it is safer," she told DW.

Five years of war

Yida lies just inside South Sudan, just 15 kilometers (9 miles) from the border with Sudan. The border is controlled by the SPLA (the army of South Sudan) and rebels from SPLM-North (a banned militant organization opposed to the government of Sudan). The rebels fought alongside the SPLA during the South Sudanese struggle for independence from Khartoum. When South Sudan finally ceded from Sudan in 2011, their new common border left the Nuba Mountains on the Sudanese side. Since then Khartoum has sought to flush out the rebels with aerial bombing raids. Hundreds of civilian targets, schools, homes and hospitals, have been hit.

The UN is moving the Yida refugees to an official camp at Ajuong Thok, which is about an hour's drive away. Fatoumata said that if new arrivals wanted assistance they would have to go and register there.

The camp, though, was nearly full. "We have 40,000 refugees there," she said. Another camp at Pamir has yet to become operational.

In the five years since the start of the war in the Nuba Mountains, nearly a quarter of a million Sudanese refugees have fled to South Sudan, mostly to Unity and Upper Nile states, the UNHCR said.

1.7 million South Sudanese have been internally displaced by two years of civil war in which tens of thousands of civilians have been killed.