Mankien sits in Mayom County in the northwest of Unity State, in the Greater Upper Nile region. It is primarily a Bul Nuer town, set in the open savannah southwest of Mayom. The fact that has shaped its recent history is geological: the town lies inside the Block 4 oil concession, one of several oilfields that Sudan began developing in the 1990s with Canadian, Chinese, and Malaysian investment. Oil transformed this region from a forgotten pastoral periphery into a strategic asset that the central government in Khartoum was willing to defend at very high human cost, and which the SPLA was correspondingly determined to disrupt. The Bul Nuer, who had lived here for generations tending cattle and sorghum, found themselves living on top of a resource that the world wanted and that their own armies could not protect them from.

In March 1998 Major General Paulino Matiep announced in Mankien the formation of his South Sudan Unity Army, recruiting Bul Nuer boys and men with weapons provided by Khartoum. This was one of several proxy militias the Sudanese government used to defend the oilfields without committing its own overstretched army. Matiep's presence turned Mankien into a garrison town. In July 1999 SSDN Commander Tito Biel, who had been armed by the SPLA, attacked Matiep's forces and pushed them almost back to their headquarters. In September 1999 Commander Peter Gatdet defected from the government side and took control of Mankien, capturing its arms depots. The struggle between militias was interpreted by observers at the time as a scramble among pro-government factions over who would ultimately control the oil revenues. In December 1998 the World Food Programme delivered its first shipment of food to Mankien in four months, an indication of how bad the pre-famine conditions in Unity State had become.

Between 1999 and 2002 Mankien passed through several cycles of occupation, bombing, and counter-attack. Antonovs rolled oil drums packed with explosives out of their rear cargo doors at altitudes where no radar would see them. The drums fell roughly where gravity sent them. Sometimes they hit military targets. More often they hit civilian settlements, cattle camps, water points. In April 2000, Khartoum launched an offensive of several hundred Baggara horsemen from the north, supported by artillery and helicopter gunships; Peter Gadet repelled it. The January 2002 assault that finally destroyed the town came after weeks of bombing. Refugees from Mayom poured into Mankien and then were caught by its destruction. Aid workers were denied flight access for long periods. The town was one of many in the oil belt whose people bore the cost of a strategic resource they did not benefit from.

After the 2005 Comprehensive Peace Agreement, a humanitarian survey of the region around Mankien found that 4% of the population was blind and almost 8% had poor vision, a consequence of untreated trachoma and other diseases that had gone unaddressed during the war. In April 2011, as South Sudan prepared for independence, the town was briefly occupied by forces loyal to Peter Gadet Yak, who had changed sides again and was now challenging the SPLA. In May 2011, after further fighting when Gadet's forces attacked from his home village of Ruadnyibol, the Mayom county commissioner reported that about 7,800 huts had been burned. Norwegian People's Aid, clearing mines in the area, noted that Unity State remained one of the most contaminated landscapes in South Sudan, with 'several minefields and a high number of abandoned ordnance contaminating huge areas of land.' The Bul Nuer who rebuild Mankien after each round of destruction do so on top of ordnance they cannot see, in a country whose oil revenues have not reached them. Their town is a footprint in the grass that keeps getting traced again.