Peace did not last long. By the end of 2013, fighting in Juba, the capital, between forces loyal to Kiir and Machar had erupted. Their respective tribes — Dinka, the largest, and Nuer, the second-largest — had long clashed over resources including land and cattle. The fighting quickly spread to the villages, fueled by outside weapons that in the years that followed would be funneled through neighboring countries in violation of arms embargoes. An estimated 400,000 people were killed in the fighting, according to a study funded by the State Department.
